Windows Forms controls are reusable
components that encapsulate user interface
functionality and are used in client side
Windows applications. A Button is a control,
which is an interactive component that
enables users to communicate with an
application which we click and release to
perform some actions.
The Button control represents a standard
button that reacts to a Click event. A Button
can be clicked by using the mouse, ENTER
key, or SPACEBAR if the button has focus.
When you want to change display text of the
Button , you can change the Text property of
the button.
continue reading: http://tutorialslodge.com/button-control/