Push Button

A push button can be connected to a circuit to momentarily finish a circuit. The push button functions by having two rows of internal connections, as illustrated below.

A generic push button is connected internally in two rows
For this reason it is only necessary to connect to two of the four pins to connect the button to a circuit.

As long as the button is not pressed, the circuit is incomplete and the wires on each side are disconnected. When the button is pressed the circuit is completed, as shown below.