The Mac makes it easy to have multiple applications — Mail, Safari, iTunes, Pages, iChat, iPhoto and others — open at the same time. So how do you quickly switch from Safari, let’s say, to Mail?
Just hold down the Command key and press the Tab key (Command-Tab). Mac OS X immediately displays a mini-Dock with icons for each of your open applications. At the left side of the mini-Dock, you’ll see the icon for your current application. Next to it (and highlighted), you’ll find the icon for the application you last used. Each time you press the Tab key (without releasing the Command key), you can cycle through your open applications.
One more tip: You can also use the Left Arrow and Right Arrow keys to navigate your open applications.