That big expanse of space that takes up the majority of your screen real estate is called the desktop. This is where you do most of your work; applications, files, and folders get opened on the desktop. If you insert a CD or DVD into your Mac, its icon shows up on the desktop. When you connect an external hard drive or iPod, or connect to an iDisk (if you or someone you know has a .Mac account), the volume mounts on the desktop. You can also store folders and files on it too.
This article applies to Mac OS X v10.5 and earlier. For Mac OS X v10.6 or later information, see this article instead.
Here's a sample of our Mac desktop:
You can move applications, folders, and files onto your desktop as long as the move doesn't affect computer operation.
Think of your Mac desktop like any standard office or school desktop, though this one is free of pencil holders, tacky knick-knacks, and coffee ring stains. Then again, your Mac does contain a variety of familiar desktop accoutrements, including sticky notes, a calendar, address book, calculator, and more—we'll introduce these “widgets” in the "Dashboard" lesson.
When you click on the desktop, the Finder becomes the active application. Same thing goes for selecting any item on the desktop. In other words, if you were, say, reading email in Mail (the email application that comes with Mac OS X), Mail would be the active application. The moment you click on the desktop, the Finder becomes active, though Mail will still run in the background.
Keep your desktop organized
When you first get a Mac, the only thing you'll find on the desktop is your hard disk icon. If you'd like, you can store other frequently-used things on your desktop, though you might also want to consider creating an alias to the item in the Dock. For example, if you plan on doing a lot of downloading, you might want to create a folder on the desktop (press the Command-Shift-N keys on your keyboard all at once), name it Downloads, and have Safari (the default web browser in Leopard) download all files to it.
If you have a few scattered picture files littering your desktop, either stick them in your Pictures folder or, if you prefer to keep them on your desktop, create a new folder called My Pics (or whatever you want to call it) and move them in there. You might even want to create new subfolders to organize your pictures by subject. For organization's sake, try not to put everything you create, save, download, or move onto the desktop. The more icons you add to your desktop collection, the harder it'll be to try and find files later.
Tip: Check out "The Menu Bar" lesson to find out how to make your Mac organize and clean up your messy desktop for you.