Hopefully by now, you have begun to appreciate the Fast User Switching feature in Mac OS X. This feature allows multiple users on one machine to quickly switch back and forth, leaving applications and files open for you to use later. The idea is that it's a fast way to switch between users (I wonder how they came up with such a catchy name?).

"I only have one user on my machine, so there is no need to use it", you say? Let's re-think this scenario. For privacy reasons, there are really two great ways to ensure no one hops on to your Mac when you leave the desk for a few minutes. The first way is to use a password-protected screensaver. That's not a bad way to do it, especially if you use a hot corner with Expose (simply drag your mouse to the corner as you walk away). The problem with that, is that it requires you to enter your password a LOT throughout the day.

Another way to achieve this is by logging out of your account. When you do this, of course, all applications you have open, and all the work you are working on, needs to be closed first. Then when you log back on, you have to re-open everything. This can be a pain, for obvious reasons.

Let's explore the Fast User Switching feature. With this turned on (System Preferences -> Accounts, then click on "Login Options"), it adds a new section to your menu bar which shows the name (either short or long name) of the person currently logged on. When you click on this name, a menu will appear:

Notice that one of the options is to go to the Login Window. By choosing this, it leaves your account logged in (as well as all applications and files open), but locks it so that no one else can access it without your password.

So even if you only have one user on your Mac, it still makes a lot of sense to use Fast User Switching!