A modifier key is a key on a computer’s keyboard which is used with another key by pressing them together at the same time.
The various modifier keys are:
Shift
Alt (Alternate)
AltGr (Alternate Graphic)
Ctrl (Control)
Win (Windows Logo) – generally found on Windows keyboards
◆ – Meta key, found on MIT, Sun Microsystems keyboards and Symbolics.
Fn (Function) – present on small-layout keyboard, usually on laptops and notebooks.
Uses:
Example: Ctrl + A -> Selects the entire text or selects all files together.