12.1. Introducing Accounts
The concept of user accounts is central to Mac OS X's security approach. Like the Unix
under its skin (and also like Windows XP and Vista), 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 (Figure 12-1).
Upon doing so, you discover the Macintosh universe just as you left it, including these
• Your documents, files, and folders.
• Your preference settings in 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 pauses at startup time to demand the name and password you made up
when you installed Mac OS X, because Apple's installer automatically turns on
something called automatic login (Section 12.5). You will be using one of these accounts,
though, whether you realize it or not.
Furthermore, when you're stuck in line at the Department of Motor Vehicles, you may
find the concepts presented here worth skimming, as certain elements of this multiple-
user system may intrude upon your solo activities—and figure in the discussions in this
book—from time to time.
Tip: Even if you don't share your Mac with anyone and don't create any other accounts,
you might still be tempted to learn about the accounts feature because of its ability to
password-protect the entire computer. All you have to do is to turn off the automatic
login feature described on Section 12.5. Thereafter, your Mac is protected from
unauthorized fiddling when you're away from your desk or when your laptop is stolen.
12.1.1. The First Account
When you first installed Mac OS X, whether it was 10.5 or an earlier version, you were
asked for a name and password. You may not have realized it at the time, but you were
creating the first user account on your Macintosh. Since that fateful day, you may have
made a number of changes to your desktop—adjusted the Dock settings, set up your
folders and desktop the way you like them, added some favorites to your Web browser,
and so on—without realizing that you were actually making these changes only to your
You've probably been saving your documents into your own Home folder, which is the
cornerstone of your own account. This folder, generally named after you and stashed in
the Users folder on your hard drive, stores not only your own work, but also your
preference settings for all the programs you use, special fonts that you've installed, your
own email collection, and so on.
Now then: Suppose you create an account for a second person. When she turns on the
computer and signs in, she finds the desktop exactly the way it was factory-installed by
Apple—stunning Earth-in-space desktop picture, Dock along the bottom, the default Web
browser home page, and so on. She can make the same kinds of changes to the Mac that
you've made, but nothing she does affects your environment the next time you log in.
In other words, the multiple-accounts feature has two components: first, a convenience
element that hides everyone else's junk; and second, a security element that protects both
the Mac's system software and everybody's work.
Figure 12-1. When you set up several accounts, you don't turn on the Mac so much
as sign into it. A command in the menu called Log Out summons this signin
screen, as does the Accounts menu described later in this chapter. Click your own
name, and type your password (if any), to get past this box and into your own stuff.