It depends on what you're trying to say. "key" is not only a button on a keyboard or a keypad (hence the name) but it's also a code. A key is something that opens, enables or unlocks something. The solution to a puzzle is often reffered to as a "key". The legend on a map is sometimes reffered to as a "key". A list of common mathematical equations and answers are reffered to as a "key". A code or serial number that unlocks a piece of software is a "software key".Originally Posted by blacknomi
So yes, you can use key and button interchangeably in most cases. It's the few times that you can't use them as such you need to be careful of.