Similar to the shift key, the control key is a modifier key that performs an advanced operation when pressed in conjunction with another key. An example would be Ctrl + Z which is a keyboard shortcut for Undo, a common shortcut in a Windows based environment.
Similar to the shift key, the control key is a modifier key that performs an advanced operation when pressed in conjunction with another key. An example would be Ctrl + Z which is a keyboard shortcut for Undo, a common shortcut in a Windows based environment. In accordance with international standards the Control Key is usually located on the bottom left side of the keyboard and almost all modern day keyboards include one on the right side as well.
This image of a Windows Ctrl key is in the public domain:
More on the Control Key in its Wikipedia page.