Virtual desktops are a very useful tool for organizing your virtual workspace. Windows, OSX, and Linux all have their versions. Linux has by far the most polished and natural-feeling virtual desktop setup (and with Compiz or Beryl, the sexiest, as seen above). Windows Desktop Manager is fairly clunky, but functional. There are also many third-party options for Windows. OSX introduced virtual desktops in v10.5, called “Spaces,” which works similarly to Linux’s native virtual desktop management.
Virtual desktops allow the user to group open software applications by placing them on separate desktops. For example, you might want your timekeeping software open on one, your documents related to a motion for summary judgment you are preparing on another, your documents for drafting a settlement demand letter on another, etc. Four is the usual amount, but you can have many more.
When you minimize a window, you make that program “inactive.” The same is true when you leave a virtual desktop (except, as far as I can tell, in the Windows implementation). Those programs use less memory than when the desktop is in focus. So you can have many programs open and ready to be used, but not clogging your taskbar (except in the Windows version). You should be able to switch a program between desktops or have it show up on all desktops, as well. You might want to see your timer on all workspaces, for example.
If you have not given virtual desktops a try, do it now. You’ll find you can sort your open applications and “multitask” far more effectively. Or just separate your work from your personal activities so you can easily flip back to work if your boss (if you have one) walks by.