The concept of user accounts is central to Tiger’s security approach. Like the Unix under its skin (and also like Windows XP and Windows 2000), Mac OS X is designed from the ground up to be a multiple-user operating system. You can configure a Mac OS X machine so that everyone must log in—that is, you have to click or type your name and type in a password—when the computer turns on.
Upon doing so, you discover the Macintosh universe just as you left it, including these elements:
Your documents, files, and folders
Your preference settings in just about every program you use: Web browser bookmarks and preferred home page; desktop picture, screen saver, and language; icons on the desktop and in the Dock—and the size and position of the Dock itself; and so on
Email account(s), including personal information and mailboxes
Your personally installed programs and fonts
Your choice of programs that launch automatically at startup
This system means that several different people can use it throughout the day, without disrupting each other’s files and settings. It also protects the Mac from getting fouled up by mischievous (or bumbling) students, employees, and hackers.
If you’re the only person who uses your Mac, you can safely skip most of this chapter. The Mac never asks you for the name and password you made up when you installed Mac OS X (at least not at startup time), because Apple’s installer automatically turns on something called automatic login (Setting Up the Login Process ...