The Desktop

The desktop lies behind all other components on your screen. When no windows are visible, the desktop is that part of the screen between the top and bottom panels. You can place files and folders on the desktop that you want to have easy access to.

The desktop also has several special objects on it:

The Computer icon gives you access to CDs, removable media such as floppy disks, and also the entire filesystem (also known as the root filesystem). By default, you do not have the security permissions to read other users' files or edit system files, but you may need to do so something such as configure a web server on the computer.
Your Home Folder, labelled username's Home, where all of your personal files are kept. You can also open this folder from the Places menu.
The Trash is a special folder in which to place files and folders you no longer need. For more on this, see Section 6.6.19 ― Using Trash.
When you insert a CD, a flash drive, or other removable media, or a device containing files such as a music player or a digital camera, an icon representing this device will appear on the desktop.

As you work with your computer, the desktop becomes obscured by the windows you are working with. To quickly reveal the desktop by minimizing all windows, you can do one of the following:

Click on the Show Desktop button at the far left of the bottom panel.
Press Ctrl+Alt+D.

Either action will also restore your windows to their previous state. Alternatively, you can switch to another workspace to see the desktop.

You can change the colour of the desktop background or the image displayed there. For more on this, see Section 8.2.1.2 ― Desktop Background Preferences.

The files and folders you put on the desktop are stored in a special folder within your Home Folder, called Desktop. Like any other folder, you can put files and other folders directly into it. The only difference is that anything placed into the Desktop folder will then show up on desktop itself.

GNOME Desktop User Guide

The Desktop