Alt + Tab
Switch between open applications in all versions of Windows. Reverse the direction by pressing Alt + Shift + Tab at the same time.
Ctrl + Tab
Switches between program groups, tabs, or document windows in applications that support this feature. Reverse the direction by pressing Ctrl + Shift + Tab at the same time.
Alt + double-click
Display the properties of the object you double-click on in Windows 95 and later. For example, doing this on a file would display its properties.
Alt + Print Screen
Create a screen shot only for the active program window in all versions of Windows. For example, if you opened the calculator and did this only the calculator window would be created as a screen shot. If just the Print Screen key is pressed the whole screen will be made into a screen shot.
Ctrl + Alt + Del
Open the Windows option screen for locking computer, switching user, Task Manager, etc. in later versions of Windows. Pressing Ctrl+Alt+Del multiple times will reboot the computer.
Ctrl + Shift + Esc
Immediately bring up the Windows Task Manager in Windows 2000 and later.
Ctrl + Esc
Open the Windows Start menu in most versions of Windows. In Windows 8 this will open the Start screen and in Windows 3.x this would bring up the Task Manager.
Alt + Esc
Switch between open applications on Taskbar in Windows 95 and later.
Alt + Space bar
Drops down the window control menu for the currently open Windows program in Windows 95 and later.
Alt + Enter
Opens properties window of selected icon or program in Windows 95 and later.
Alt + Space bar
Open the control menu for the current window open in all versions of Windows.
Shift + Del
Will delete any file or other object without throwing it into the Recycle Bin in Windows 95 and later.
Hold down the Shift key
When putting in an audio CD or other CD that uses Autoplay, holding down the Shift key will prevent that CD from playing.