Archive for WINDOWS OS

Windows OS

An operating system, sometimes called an “OS”, is the system software the computer uses to function properly. Operating systems act as a link between  the user and the programs users uses on a computer. Different types of computers use different types of operating systems.

Windows Operating SystemWINDOWS FEATURES

Most PCs run on an operating system called Windows. These particular tutorial deals with the Windows XP professional version of the Windows operating system. The operating system is what allows you as the user to access the information in the computer. To understand how to use a computer, it is important to know several features of the Windows system.


The desktop is the area you see when the computer is not running applications. It consists of the icons on top of it, as well as the Start button and other features. The desktop can be used to temporarily store information or to move around documents and windows.


Icons are little pictures that represent different programs or saved items. Double-clicking on the icon accesses the information icons represent.


Each application opened will appear in its own window, or its own little section of the screen. Windows can be moved and resized so that you can operate many different applications at the same time. To learn how to manipulate windows, refer to the Manipulating Windows portion of Level.

Dialogue Box

When you ask the computer to do certain commands, such as to save your work, the computer will need more information from you, and this will appear in a dialogue box. These boxes contain options and commands for the computer to execute.

Start Menu

In the lower left-hand corner of the Windows screen is the Start button. When you click on the button a menu will appear, which we will call the Start menu. This menu gives you access to all the different parts and functions of the computer.

Task Bar

At the very bottom of the screen is a horizontal bar called the task bar. This bar contains (from left to right) the Start button, shortcuts to various programs, minimized programs, and another section of shortcuts that includes sound volume, printers and the time.

Tab Menu

Tab menus, which are often present in dialogue boxes, are menus that represent many different “pages” of information. To access each “page,” click on the tab at the top of the dialogue box.


First of all, you will need to turn the computer on. Do this by pushing the power button on the front of the computer unit. The computer takes a few minutes to start up, so be patient.


To shut down, click with your mouse on the button in the lower left-hand corner of the screen labeled Start. On the menu that pops up, click on Turn off computer. This will bring up a dialogue box with more options in it. Click “Turn Off.” It is important to remember that turning off the computer by pressing the power button without going through the shut down process may damage the computer.


When a computer is left alone for a while, it goes into “sleep” or “stand by” mode to save energy. In stand by mode, the computer slows down its inner processes because they are not being used. The computer also blacks out the monitor. If you wish to use a computer and the monitor is dark, check to see if it is in stand by before you try to start it up. Usually, the computer has a green light on or near the power button that signifies that it is on, but in stand by mode. To “wake it up,” move the mouse or hit a key on the keyboard. In about 8-10 seconds the computer will wake up and be fully functional. If you do not realize that the computer is in stand by and you try to turn it on with the power button, the computer will wake up and a dialogue box will appear, but it will not damage the computer.


To open an application you have two options:

1. Open the Start menu and click on the name of the application.

2. Find the icon for the application and either double click it or right click and choose



To close an application:

1. Most applications can be closed by choosing “File” menu and selecting Quit or Exit.

2. If no file menu is available, click the “X” button in the upper right-hand corner of the application’s window.


Following is a list of common features that can be implemented on all windows.

MAXIMIZE This function allows you to concentrate on one application by making its window cover the entire screen.


This function allows you to keep an application running, but remove it from the desktop area so that other applications can be accessed. The minimized program becomes a bar at the bottom of the screen, and can be accessed by clicking on the bar.


If an application window is not maximized, it can be resized so that more or less content can be seen. If you move your mouse pointer to one of the edges of the window, it will become a two-way arrow. At this point, hold down the left mouse button and drag the perimeter of the window in or out. When you release the mouse button, the window will resize to your specifications.


This function closes and exits the application you are running. However, if you are running an application such as Microsoft Word, the window of each document will have a close button, and clicking this button will only close that particular document, and not the entire program. It is important to always save your work before using the close feature, as any unsaved changes will be lost.


Saving material onto a disk stores that material so that it can be accessed again. Any work you do on the computer should be saved, including papers and other assignments. Although you may be working in different applications, the saving procedure is generally the same.

1. Insert a disk into the correct disk drive.

2. Go under the File menu in the application, and choose “Save As.”

3. When the Save As dialogue box appears, click the arrow button next to the Save In box. This will cause a menu of save options to appear.

4. To save on your removable disk, choose either the 3 1/2″ Floppy Drive or the Zip Drive accordingly.

5. Type in a filename that will identify your document at the bottom of the box.

6. Click the Save button located in the lower right-hand corner of the box.

7. Save work as you continue, you only need to click on the save icon or go under File > Save.



Save often. This is by far the most important step in the saving procedure. The more you save, the less chance you have of losing any of your hard work. Errors and freeze-ups can occur, and unsaved work will be lost. Also, always save before printing because this is the time when many errors occur.

Use specific filenames. When naming your saved works, label them with detailed names so for easier identification when you go to find them again.


Back up your saved works. Disks have been known not to not certain saved works because of errors. Make sure you save important works on two disks so that if one disk fails, you have a backup copy on another disk.



Most labs have one or two printers that are shared by many computers in the lab. As with saving, most applications print in a similar fashion. Follow these steps to print your work.

1. Save your work. Computers sometimes freeze when you ask them to print, and all of your work may be lost.

2. Go under the File menu to Print.

3. When the dialogue box appears, check to make sure that the printer listed is the printer in the lab you are in. If it is not, click on the arrow to the right of the printer name and choose the correct printer.

4. Choose how many copies you would like printed.

5. Decide if you only want a portion of the work to be printed and choose the number of pages to print.

6. Click OK.


If you choose to delete an item from your disk or from the computer’s hard drive, you will need to access the Recycle Bin. It is important to remember that you may only delete items from the hard drive that you have created. To delete an item from a disk or the hard drive, use the following steps.

1. If it is on a removable disk, first insert the disk into the correct drive. Next doubleclick on the My Computer icon on the Desktop. Choose the drive that the item is located on by double clicking the appropriate drive icon. Open the file that the item is located in.

2. Left-click on the item that you wish to delete and hold the button down.

3. Drag the item out of the window it is in and place it over the Recycle Bin located on the Desktop.

4. When the Recycle Bin is highlighted, release the button. The item should disappear from the drive.

5. When the dialogue box appears asking you if you are sure you want to delete this item, click Yes.


When you deposit items in the Recycle Bin, they will not be permanently removed from the computers memory without you telling it to do so. If you decide you still want to keep something, double-click on the Recycle Bin and drag the item back out. To permanently erase an item from the computer, right-click on the Recycle Bin and choose Empty Recycle Bin. Remember, once you empty the Recycle Bin, the items inside will be permanently erased from the computer’s memory.



Located in the Start menu is the Windows Help and Support option. If you have any problems with the Windows systems or have questions about how to do something, the Help option may have the answer. If the computer does have the Help option, follow these steps to use it.

  1. Select Help and Support from the Start menu.

2.   Choose to view Help and Support by one of the following categories: Index,

Support, History, Favorites, or Options. Select the category that you would like by clicking the appropriate button.

              3. Click on the heading of your choice in the list located on the left side of the screen, or if you are in the Index category, click on Locate in Contents to type in a keyword.


Computers are powerful machines that can aid us in many of our everyday tasks. Computers are, however, rather fragile and should be treated in a respectful manner. Following is a list of dos and don’ts that will preserve the life of the computer while letting you get the most out of the machine.


Save your work often. This prevents the loss of hours of work.

Back up your work in case of disk malfunction.

Ask lab staff for help at any time.

Shut down the computer when you are finished. This means do not press the power button, but go through the shut down procedure under the Start menu.



Eat or drink around a computer. Spilled drinks and food can harm a computer’s hardware. Food and drinks are not allowed in on-campus labs, but if for some reason you do spill something on a computer, report it to the staff on duty immediately.

Strike the computer or physically abuse it.

Print more than one copy of your work in the computer labs. The printers are for printing work, and not to do the job of a copy machine.

Change the settings of on-campus computers. If you are having problems, please ask the lab staff for help.


In the bottom left-hand corner of the Windows screen is a button labeled “Start.” This button displays a menu that gives you access to many of the computer’s features. Once the Start menu is opened, all you have to do is highlight what you want and more options will appear. Here we will discuss the many features and uses of the Start menu from top to bottom.


New Office Document

This feature acts as a shortcut for opening a new document in Microsoft Office. You can choose from a variety of document formats.

Open Office Document

This feature acts as a shortcut for accessing a saved document or file.

Windows Catalog

This item opens Internet Explorer to a site in which you can purchase products built for Windows systems.

Windows Update

This item opens Internet Explorer to a site in which you can download updates for your Windows operating system.


This prompt will open another menu filled with more options. These options are all programs that the computer can run. To see what the Programs menu has to offer, refer to the Programs page.

Documents :This item allows you to temporarily store saved works.


This menu contains access to the Control Panel as well as your Network Connections; Printers and Faxes; and Taskbar and Start Menu. Through these options you can customize the appearance and functions of your computer.


This menu allows you to find anything on the computer or on the Internet.

Help and Support

This feature will open the Windows Help and Support Menu.


This item allows you to run programs located on a disk, CD, or on the Internet.

Log Off

This allows you to log off the computer.

Turn Off Computer

When this phrase is clicked, the Shut Down menu will appear, allowing you to hibernate, shut down, or restart the computer.


There are often times when you are working on a computer and it “freezes”-that is the mouse and keyboard no longer affect the computer. No matter what you click on, nothing happens. Sometimes the mouse cursor won’t even move on the screen. This may happen for a number of reasons including memory fill-up or glitches in the system. This problem, however, can often be fixed. If your screen freezes (this is sometimes referred to as crashing) and nothing seems to be happening, use these steps to unfreeze it. It is important to remember, however, that these steps will not always fix the situation, and sometimes the only thing left to do is turn the computer off by pushing the power button.


1. Press Ctrl+Alt+Del. This will cause the computer to show a dialogue box that lists the current applications that are running on the computer. Most likely, the application you are using will be listed here at the top, often with the phrase “not responding” behind it. This means that the particular application you are running has frozen and you need to shut this application down.

2. Click on the application causing the problem, and then click the End Task button.

3. Another dialogue box will appear and ask you to confirm your decision. Click End Task again. Under normal circumstances this process will shut down the problematic application and the computer will be restored to its previous running state. It will also give you the option to shut the computer down if you choose to do so.

4. Sometimes, however, clicking on a particular task and trying to end it will not always do the trick. The only option left is to press Ctrl+Alt+Del again, which will cause the computer to restart. Any unsaved work will be lost in this instance, so make sure you save often to avoid redoing work.

There are a number of things you can do to prevent and avoid freezes and crashes. Only open the applications you will be using-extra applications take up more memory and can cause freeze-ups.

When you sit down at the computer, check to see that no applications were left running by the previous user. These running applications will often be minimized at the bottom of the screen.

If you are using an application that requires a lot of memory, such as PowerPoint or PhotoShop, do not attempt to open other programs, as a freeze-up may occur when memory fills up.


To access the Internet from a computer, you need to open a web browser. A web browser is a program such as Netscape Communicator or Internet Explorer that allows you to surf the net. There are basically three ways to access the Internet from a PC.

1. Double-click the web browser icon on the desktop.

2. Click Start Menu –> Programs –>Internet, and then click on the web browser of your choice.

3. Click the web browser shortcut on the task bar located at the bottom of the screen.


Keyboard shortcuts are key commands that allow you to accomplish various tasks. Instead of using your mouse to go through menus and sub-menus, you can use keyboard shortcuts to do common tasks like saving, copying, or pasting. Most people find using key shortcuts to be a faster and easier way to type. Listed below are some of the most common keyboard shortcuts in alphabetical order.

Close CTRL+W



Delete DEL

Exit ESC

Find CTRL+F3

Help F1

Minimize Window Windows Key*+M

Move to Recycling CTRL+DEL

New Folder/Document CTRL+N


Open Start Menu Windows Key*

Paste CTRL+V

Page Up/Down Page Up/Down Keys

Print CTRL+P

Print Screen ALT+Print Screen Key

Quit ALT+F4

Reboot/Restart CTRL+ALT+DEL


Select All CTRL+A


* Not all keyboards have the Windows key.

CTRL is the abbreviation for the Control key.

DEL is the abbreviation for the Delete key.


When you right-click your mouse, a small menu will appear. This is the right-click menu, and it contains a list of the common tasks for whatever program you’re currently using. If you use the right-click menu you can leave your cursor in roughly the same spot, which makes resuming your task easier. Each program’s right-click menu will be unique and look slightly different from others, but most follow the same general format. As an example, the following picture is what a menu would look like if you right-clicked on the desktop.


Arrows along the right side of the menu signal that there is a sub-menu for that particular item. These sub-menus contain even more shortcuts that are grouped together in a category.

To exit the right-click menu, left-click on any part of the screen besides the menu.


If you are familiar with Internet Explorer, you know that it helps you find web pages and information on the Internet. There is another kind of explorer on your computer: Windows Explorer. The basic idea behind Windows Explorer is very similar to Internet Explorer. The program lets you look through all of the files and folders on your computer. You can even open, copy, cut, and paste your files from inside Windows Explorer.


The frame on the left shows the contents of your entire computer. To see what’s inside of a particular directory, click on the plus (+) sign. To hide what’s inside of a directory, click the minus (-) sign that replaced the plus sign.

The frame on the right side shows you only the contents of the folder or directory that you’ve selected. Sometimes you must go through several directories and folders to get to the file you want.

WINDOWS Component and its description

Component of Windows OS Description Introduced With Windows Version
Control Panel
Control Panel Allows users to view and manipulate basic system settings and controls, such as adding hardware, adding and removing software, controlling user accounts, changing accessibility options, and so on. Windows 1.0
Device Manager Allows the user to display and control the hardware attached to the computer, and control what device drivers are used. Windows 95
Windows Mobility Center Centralizes the most relevant information related to mobile computing. Windows Vista
Windows Action Center Centralizes and reports on the status of anti-virus, Automatic Updates, Windows Firewall, and other security-related components of the operating system. Windows XP SP2
Administrative Tools
Microsoft Management Console Provides system administrators and advanced users with a flexible interface through which they may configure and monitor the system. Windows NT 4.0 Option Pack
Windows System Assessment Tool A built-in benchmarking tool that analyzes the different subsystems (graphics, memory, etc.), and uses the results to allow for comparison to other Windows Vista systems, and for software optimizations. It rates the computer’s performance using the Windows Experience Index. Windows Vista
System Restore Allows for the rolling back of system files, registry keys, installed programs, etc., to a previous state in the event of a system failure. Windows Me
Windows Recovery Environment Helps diagnose and recover from serious errors which may be preventing Windows from booting successfully, or restore the computer to a previous state using System Restore or a backup image. Windows Vista
Windows Disk Defragmenter Rearranges files stored on a hard disk to occupy contiguous storage locations in order to optimize computer performance. Windows 95, Windows 2000
Event Viewer Lets administrators and users view the event logs on a local or remote machine. Windows NT 3.1
Resource Monitor (or Reliability and Performance Monitor) Lets administrators view current system reliability and performance trends over time. Windows Vista
Logical Disk Manager A logical volume manager developed by Microsoft in conjunction with Veritas Software. Windows NT 4.0 (as a separate Tool) 2000 (integrated in the Management Console)
Registry Editor Edits the Windows registry. Windows 3.1
Task Scheduler Allows users to script tasks for running during scheduled intervals Microsoft Plus! for Windows 95
Software installation and deployment
Windows Update An online service which provides critical updates, service packs, device drivers, and other updates. A variation called Microsoft Update also provides software updates for several Microsoft products. Windows 98
Windows Installer A packaging format and engine for the installation, maintenance, and removal of software. Includes a GUI framework, automatic generation of the uninstallation sequence and deployment capabilities for corporate networks. Windows 2000
ClickOnce Technology for deploying .NET Framework-based software via web pages, with automatic update capabilities. Intended for per-user only applications. .NET Framework 2.0

User interface

Component Description Introduced
Windows Aero The file that contains the Windows Aero theme for Windows Vista and Windows 7. Windows Vista
Metro UI Metro is a new design language that replaces Windows Aero. It has a new tile interface that shows important information. Windows 8
Windows Shell The most visible and recognizable aspect of Microsoft Windows. The shell is the container inside of which the entire graphical user interface is presented, including the taskbar, the desktop, Windows Explorer, as well as many of the dialog boxes and interface controls. In Windows Vista, a new compositing glass-like user interface called Windows Aero has been shown. Windows 95
Windows Explorer Provides an interface for accessing the file systems, launching applications, and performing common tasks such as viewing and printing pictures. Windows 95
Windows Search Starting with Windows Vista, search is a tightly shell-integrated component of Windows. A downloadable Windows Desktop Search software is available for Windows XP and older versions. Windows Vista, downloadable for older versions
Special Folders Folders which are presented to the user through an interface as an abstract concept, instead of an absolute path. This makes it possible for an application to locate where certain kinds of files can be found, regardless of what version or language of operating system is being used. See also, Windows Shell namespace. Windows 95
Start menu Serves as the central launching point for applications. It provides a customizable, nested list of programs for the user to launch, as well as a list of most recently opened documents, a way to find files and get help, and access to the system settings.By default, the Start Button is visible at all times in the lower left-hand corner of the screen. Windows 95
Taskbar The application desktop bar which is used to launch and monitor applications. Windows 95
Desktop Gadget Gallery A screen to place gadgets anywhere. Windows 7
File associations Used to open a file with the correct program. File associations can be uniquely assigned to specific actions, known as verbs. Windows 3.0

Applications and utilities

Component Description Introduced
Windows Easy Transfer Used to transfer many files at once from one computer to another. Windows Vista
Windows Contacts Keeps a single list of contacts that can be shared by multiple programs. Windows Vista
Calculator A calculation application. Windows 1.0
Character Map Utility to view and search characters in a font, copy them to the clipboard and view their Windows Alt keycodes and Unicode names Windows 3.1
Paint A simple graphics painting program. Windows 1.0
Windows To Go A utility to create bootable versions of Windows 8, called Windows To Go Windows 8
Notepad A simple text editor. Windows 1.0
Narrator A screen reader utility that reads dialog boxes and window controls in a number of the more basic applications for Windows. Windows 2000
Sound Recorder A simple audio recording program that can record from a microphone or headset, and save the results in WAVE format and Windows Media Audio format in some Windows versions. Windows 3.1
Command Prompt A text-based shell (command line interpreter) that provides a command line interface to the operating system. Windows 1.0
WordPad A simple word processor that is more advanced than Notepad. It has facilities to format and print text, but lacks intermediate features such as a spell checker and thesaurus. Windows 95
Private Character Editor Utility to create private use characters as defined under Unicode and various East Asian encoding schemes. Windows 3.1+ East Asian editions
Remote Desktop Connection A client implementation of the Remote Desktop Protocol; allows a user to securely connect to a computer running Terminal Services (Remote Desktop on Windows XP and Server 2003) and interact with a full desktop environment on that machine, including support for remoting of printers, audio, and drives. Windows XP, downloadable for previous Windows versions
Windows Remote Assistance Allows a user to temporarily take over a remote computer over a network or the internet to offer help with and resolve issues. Windows XP
Internet Explorer A graphical web browser and FTP client.See also: IE1, IE2, IE3, IE4, IE5, IE6, IE7, IE8, Features, History, Removal, Browser Helper Objects Microsoft Plus! for Windows 95
IExpress Allows users to create self-extracting, self-installing INF installation-based packages. Internet Explorer 6
Windows Fax and Scan An integrated faxing and image scanning application. Windows Vista, older faxing and scanning applications were present in previous Windows versions
Windows Media Player A digital media player and media library application that is used for playing audio, playing video and viewing images. In addition to being a media player, Windows Media Player includes the ability to rip music from, and copy music to compact discs, synchronize content with a digital audio player (MP3 player) or other mobile devices, and let users purchase or rent music from a number of online music stores. Windows 95
Windows Photo Viewer A simple image viewer that can play a simple slideshow Windows 7
Windows DVD Maker A DVD movie encoding and authoring software. Windows Vista
Windows Journal A notetaking application that allows for the creation of handwritten notes. Windows XP Tablet PC Edition, Vista
Windows Media Center Designed to serve as a home-entertainment hub, to be viewed from a distance up to 3 meters (~10 feet) and controlled by specially designed remote controls. Lets users browse and view pictures, videos, and music from local hard drives, optical drives, and network locations, along with viewing, recording and deferred-playing live TV. Features an interactive TV guide with scheduled recording capabilities. Can also be used for visualization of other information (like sports scores) within the interface. Windows XP Media Center Edition
Windows Task Manager Provides information about computer performance and displays details about running applications, processes, network activity, logged-in users, and system services. Windows 3.0
Disk Cleanup A utility for compacting rarely used files and removing files that are no longer required. Windows 98
Shadow Copy A graphical front end for the Shadow Copy service that lets users choose from multiple versions of a file. The shadow copy service creates multiple copies of a file as they are changed over time, so that users can revert to previous versions. Windows Vista. Windows Server 2003 included Previous Versions support only for client computers.
Snipping Tool A screen-capture tool that allows for taking screen shots (called snips). Experience Pack for Windows XP Tablet PC Edition 2005

Windows Server components

Component Acronym Description Supported by
Windows Server domain A logical group of computers that share a central directory and user database. All Windows NT-based versions
Active Directory AD A set of technologies introduced with Windows 2000 that allows administrators to assign enterprise-wide policies, deploy programs to many computers, and apply critical updates to an entire organization. Active Directory stores information and settings relating to an organization in a central, organized, accessible database. Networks can vary from a small installation with a few objects, to global-scale directories with millions of objects.
Related topics: Active Directory Service Interfaces, Flexible single master operation, IntelliMirror, Active Directory Application Mode
Windows 2000, Windows Server 2003
Domain controller DC, PDC, BDC A server that responds to security authentication requests (logging in, checking permissions, etc.) within a Windows Server domain. Prior to Windows 2000, a domain controller was either a Primary Domain Controller (PDC), of which there could only be one with this role; or a Backup Domain Controller (BDC). In Windows 2000 and later the concept of primary and secondary domain controllers were eliminated, partially to emphasize the multi-master replication technology available in Windows. All Windows NT-based versions
Group Policy GP, GPO Provides centralized management of user and computer settings in an Active Directory environment. Group policy can control a target object’s registry, NTFS security, audit and security policy, software installation, logon/logoff scripts, folder redirection, and Internet Explorer settings. Policy settings are stored in Group Policy Objects (GPOs), and may be linked to one or more sites, domains or organizational units.
Related topics: Administrative Templates
Windows 2000 and later
Internet Information Services IIS Web server Windows NT family

File systems

Component Acronym Description Supported by
File Allocation Table FAT, FAT12, FAT16 The original file systems used with MS-DOS. The standard file systems used with Windows 1.0 through Windows 95. All versions
FAT32 FAT32 Extensions to FAT supporting larger disk sizes. The standard file system for Windows 98 and Me. Windows 95 OSR2, Windows 98, Windows 2000, Windows XP, Windows Server 2003, Windows Vista
NTFS NTFS Standard file system of Windows NT; supports security via access control lists, as well as file system journaling and file-system metadata. Windows 2000 added support for reparse points (making NTFS junction points and Single instance storage possible), Hard links, file compression, and Sparse files. Encryption of data is provided by Encrypting File System. Symbolic links and transactioning of file operations via Transactional NTFS are features new to Windows Vista. Windows 95 also supports reading NTFS partitions, over a network. Windows NT, Windows 2000, Windows XP, Windows Server 2003, Windows Vista
ISO 9660 ISO 9660 (“CDFS”) The predominant file system for CD-ROM and DVD-ROM media. Windows includes support for Joliet extensions and the ISO 9660:1999 standard. ISO 9660:1999 is supported since Windows XP. MS-DOS and Windows 9x via extensions, such as MSCDEX.EXE (Microsoft CDROM Extension), natively in Windows NT
Universal Disk Format UDF A file system for storing files on optical media. It is an implementation of the ISO/IEC 13346 standard (also known as ECMA-167). It is considered to be a replacement of ISO 9660. Successive versions of Windows have supported newer versions of UDF. Windows 98, Windows 2000, Windows XP, Windows Server 2003, Windows Vista
HPFS HPFS High-Performance File system, used on OS/2 computers. Read and write capability in Windows 95 (where it also listed network computer NTFS-formatted drives as “HPFS”, even though it had no direct NTFS capabilities). HPFS write support was dropped in Windows NT 4.0 and Windows 98, and dropped altogether shortly before the release of Windows 2000. Windows 95 (Read/write), Windows 98, Windows NT (read), 3.1/3.51 (read/write/boot)

Core components

Component Acronym Description
Windows kernel (Windows NT)

Main article: Architecture of the Windows NT operating system line
Ntoskrnl.exe The Windows kernel image. Provides the kernel and executive layers of the kernel architecture, and is responsible for services such as hardware virtualization, process and memory management, etc.
hal.dll HAL Provides and handles the interaction between software and hardware via the Hardware Abstraction Layer.
Core processes (Windows NT)
System idle process SIP A counter which measures how much idle capacity the CPU has at any given time. The process runs in the background and monitors processing bandwidth, occupied memory and the Windows virtual paging file.
Session Manager Subsystem SMSS Performs several critical boot-time operations, such as the creation of environment variables, starting CSRSS, and performing file-copy operations that were queued up from before the system was booted (pending file rename operations). During system operation, it handles Windows File Protection and the creation of logon sessions via Winlogon.
Client/Server Runtime Subsystem CSRSS User-mode side of the Win32 subsystem. Provides the capability for applications to use the Windows API.
Local Security Authority Subsystem Service LSASS Responsible for enforcing the security policy on the system. Verifies users logging on to the computer and creates security tokens.
Winlogon Responsible for handling the secure attention key, loading the user profile on logon, and optionally locking the computer when a screensaver is running. On Windows NT systems prior to Windows Vista, Winlogon is also responsible for loading GINA libraries which are responsible collecting logon credentials from the user.
Svchost.exe A generic host process name for services that run from dynamic-link libraries (DLLs). Several Svchost processes are typically present on a Windows machine, each running in a different security context, depending on what privileges the contained services require.
Windows on Windows and WOW64 WoW An abstraction layer that allows legacy code to operate on more modern versions of Windows; typically this means running 16-bit Windows applications on 32-bit Windows, and 32-bit applications on 64-bit Windows.
Virtual DOS machine NTVDM Allows MS-DOS programs to run on Intel 80386 or higher computers when there is already another operating system running and controlling the hardware. Introduced in Windows 2.1; not available in any 64-bit edition of Windows.
System startup (Windows NT)

Main articles: Windows NT Startup Process and Windows Vista Startup Process
NTLDR, IA64ldr, Winload The boot loader; performs basic system initialization options such as loading the hardware abstraction layer and boot-time device drivers, prior to passing control to the Windows kernel. In versions prior to Vista, NTLDR and IA64ldr also display menus to the user if multiple operating systems are defined in boot.ini, or if F8 is pressed.
Recovery Console Provides the means for administrators to perform a limited range of tasks using a command line interface, primarily to aid in recovering from situations where Windows does not boot successfully. Used during the boot process to detect basic hardware components that may be required during the boot process.
Windows Boot Manager In Windows Vista and later operating systems, displays boot menus to the user if multiple operating systems are configured in the system’s Boot Configuration Data.
Graphical subsystem
Desktop Window Manager DWM The compositing manager introduced in Windows Vista that handles compositing and manages special effects on screen objects in a graphical user interface.
Graphics Device Interface GDI/GDI+ The kernel graphics component for representing graphical objects and transmitting them to output devices such as monitors and printers.
Windows USER The Windows USER component provides core user interface, messaging and visual elements.


This list is not all-inclusive (see also: Windows Services).

Display name Service key name Description Introduced
Active Directory Service NTDS Network Authentication Management Windows 2000 Server
Alerter service Alerter Sends administrative alerts over the network to client computers, administrators and users. Windows NT
Application Layer
Gateway service
ALG Provides support for plugins that allow network protocols to pass through Windows Firewall and work behind Internet Connection Sharing. Windows 2000
Application Management AppMgmt Processes requests to enumerate, install, and remove applications that are installed on the computer or deployed through an organization’s network. Windows 2000
Background Intelligent
Transfer Service
BITS Transfers files between machines using idle network bandwidth. Used by Windows Update, Windows Server Update Services, and Systems Management Server to deliver software updates to clients, as well as by Windows Messenger. Windows XP
Computer Browser Browser Crawls neighboring computers on the network and locates shared resources. One of the computers acts as the Master Browser and supplies this information to other computers designated as browsers. Windows for Workgroups
Distributed Link Tracking TrkWks, TrkSrv Used to track links to files on NTFS volumes. Windows uses these services to find linked files if they are renamed or moved (locally or to another machine). Windows 2000
Distributed Transaction
MSDTC Allows transactional components to be configured through COM+ by coordinating transactions that are distributed across multiple computers and/or resource managers, such as databases, message queues, file systems, and other transaction–based resource managers. Windows 2000 and later NT-based
DNS Client and Server DNSCache/DNS The client service resolves and caches DNS names. The DNS server performs DNS name resolution. Client in Windows 2000 and later NT-based,
Server in Windows NT 4.0 and later NT-based
Event Log EventLog Stores and retrieves events that can be viewed in the event viewer. Part of services.exe. Windows NT
Extensible Authentication Protocol EAPHost Provides EAP authentication to connecting clients Windows 2000
Indexing Service CISVC Indexes contents and properties of files on local and remote computers; provides rapid access to files through flexible querying language. Windows 2000 and later NT-based
Network Location Awareness NLA Manages network configurations and information, and notifies applications of changes. Windows XP
Network Store Interface Service NSIS Collects routing information of active network interfaces, shares this with other services and notifies applications of changes. Windows XP
NTLM Security Support Provider NTLMSSP Uses the NTLM MS-CHAP protocol to encapsulate and negotiate options in order to provide signed and sealed communication. Deprecated now in favor of Kerberos authentication. Windows NT
PNRP PNRPSvc Resolves domain names using PNRP. Windows XP
Plug and Play PlugPlay Enables autodetection and configuration of hardware. Windows 2000
Print Spooler Spooler Manages printer devices and moves files into memory for printing. Windows 95, Windows NT
Routing and Remote Access Service RRAS API and server software that makes it possible to create applications to administer the routing and remote access service capabilities of the operating system, to function as a network router Windows 2000
Secondary Logon (Run As…) SecLogon Allows users to run programs with a different account than the one they logged in with. Allows non-administrative accounts to perform administrative tasks.
Security Account Manager SamSs Manages user account security information. Windows NT family
System Event Notification SENS Monitors system events, such as network, power, logon, logoff, terminal services session connection and disconnection, and delivers these to applications and other system components. Windows 2000
Task Scheduler Schedule Lets users setup and schedule automated tasks. Microsoft Plus! for Windows 95
TCP/IP NetBIOS Helper LmHosts Enables support for NetBIOS over TCP/IP (NetBT) service and NetBIOS name resolution. Windows NT family
Windows Audio AudioSrv Manages audio devices for Windows-based programs. Controls all audio functions. Windows XP
Windows Error Reporting WERSvc Generates error logs and reports errors. On Windows Vista and later, it notifies of solutions. Windows XP
Windows Image Acquisition (WIA) STISvc Handles scanner and camera inputs. Windows Me
Windows Time W32Time Synchronizes the system time with external time servers. From Windows Server 2003 forward, full and compliant NTP support is provided. Windows 2000
Windows Update WUAUServ Provides updates for the operating system and its installed components. Windows XP
Wireless Zero Configuration WZCSvc (XP), WLANSvc Configures and manages 802.11 wireless adapters. Windows XP, Server 2003 only
Windows Messenger service Messenger Allows users to send pop-up messages to other computers over the network. Windows NT family
MSRPC RpcSs Provides Remote Procedure Call (RPC) technique via remotely accessible Named Pipes. Windows NT family
Volume Shadow Copy Service VSS Create multiple versions of files that change. Gained ability to store persistent snapshots in Windows Server 2003. Windows XP
WebClient Enables Windows-based programs to create and interact with Internet-based files. Windows XP
Windows Firewall/
Internet Connection Sharing
SharedAccess Internet Connection Sharing (Firewall) Windows 2000