For years, teachers, parents, and computer lab instructors struggled to answer a difficult question: How do you rig one PC so that several different people can use it throughout the day without interfering with each others' files and settings? And how do you protect a PC from damage by mischievous (or bumbling) students and employees? And now you, home network administrator, are hereby welcome to join this chorus of despair. How are you supposed to keep all the people on your network from driving each other batty?
The answer lies in user accounts. Microsoft designed both Windows XP and Windows 2000 to be multiple-user operating systems. On these machines, anyone who uses the computer must log on—click (or type) their name and type in a password—when the computer turns on. You may remember that when you first installed Windows XP or Windows 2000 or fired up a new Windows XP/2000 machine, the computer asked you for a name and password. You may not have realized it at the time, but you were creating your PC's first user account.
PCs running Windows 9x sometimes require you to log on as well, depending on how things are set up. While not as powerful (or as secure) as Windows 2000 and XP, logging into a Windows 9x computer with a separate account provides some of the same organizational benefits, but without the super-security of Windows 2000 and XP.