If you want to go out for a cup of coffee or you want a break so you can run to the rest room, but you do not want anybody to use your computer behind your back, then you can either log off your computer or lock it. The benefits of locking is that all the programs keep running as they were when you unlock the computer. So you can keep a large file downloading, lock the Windows and go out for a fresh cup of coffee. Here is how you can lock the desktop
# 2. You can press the keyboard shortcut key combination Windows Key + L and you would find your computer locked.
# 3. Press the key combination Ctrl + Alt + Del and choose Lock this computer
After your computer gets locked, you can unlock it only by entering the password. Only the user who locked the computer, or an administrator can unlock the computer locked by Windows 7.
Caution : If your account uses a blank password, then anybody can click on your account picture in the locked screen and unlock your desktop without entering any password.