Desktop is a common term for describing a desktop computer.
In software terms, desktop is the desktop environment, a GUI (Graphical User Interface) metaphor which helps in facilitating the interaction between the operating system and the user.
It is a Windows Sysinternals utility which allows the users in managing the applications on at least four virtual desktops, where all are accessible using the interface of a tray icon. In terms of the GUI or operating system, the Desktop is an organization as a system of screen icons.
It was first introduced with Windows 95, the first Microsoft Windows version. The most common desktop icons are My Computer, Internet browser, My Documents, Recycle Bin and other applications. Users can even have an access to the Windows Start Menu directly from the desktop using the Start Button available on the Taskbar and even the Windows Notification Area.
There might be a possibility that some of these icons are missing on some Windows versions, but it can be easily changed to default icons.
Windows 7 Desktop :