How to quickly switch users in Windows XP?

When the switching users feature is enabled, users can quickly switch to other user accounts without closing the programs that are running. In addition, with Fast User Switching function enabled, users can switch sessions without closing programs.

For example, User A is logged on and is browsing a webpage, user B wants to log on to check E-mail. User B can check E-mail while User A leaves the programs running.
Then, user A can still return to the session where the programs would still be running.

Please refer to the technical support from Microsoft for more details.

Article ID	279765
Last Review	2007/03/27
Title	How To Use the Fast User Switching Feature in Windows XP
Link	https://support.microsoft.com/kb/279765/en-us

Please follow the steps below to use the Fast User Switching Feature . ■ How to enable or disable Fast User Switching Feature? ■ How to switch users? ■ How to manage other users? ■ How to enable or disable Fast User Switching Feature? Click Start, and then click Control Panel. Click User Accounts. Click Change the way users log on or off. Enable  Use Fast User Switching. If the Use the Welcome screen option is enabled, users cannot select Use Fast User Switching. ■ How to switch users? By enabling Switch Users, several user accounts can log on the same computer simultaneously. Initiate the Switching User option in Welcome screen using one of the following methods. Click Start→Log off→Switch User. Press Ctrl + Alt + Delete at the same time, Open Task Manager, and click Switch User on the Processes menu. Hold down the Windows key, and then press the L key. ■ How to manage other users? With administrator's privileges, users can log other users off from the computer. In addition, users can send them a message from the session. Log off other users Press Ctrl+Alt+Delete at the same time to open Task Manager. Click the Users tab, and click the name of the user that users would like to log off. Click Yes in Logoff and Windows Task Manager respectively to log the user off from the computer. Send message to other users Press Ctrl + Alt + Delete at the same time to open Task Manager. Click the User tab, and click the name of the user users would like to send a message. Click Send Message, type the message title and message contents in Send Message and then click OK.