Buttons carry out HyperTalk commands such as taking you to another card, finding text, displaying a series of cards, and many more. HyperTalk commands are contained in SCRIPTS. You can edit scripts and you can copy and paste buttons to duplicate their scripts.
Click the HyperTalk tab to find out more about scripts.
A button can be on an individual card or in a background, where it's shared by every card that uses that background.