A push button switch is a switch that has a knob that you push to open or close the contacts. In some push button switches, you push the switch once to open the contacts and then push again to close the contacts. In other words, each time you push the switch, the contacts alternate between opened and closed. These types are commonly called latching switches. There are also non latching push button switches that only maintain the switch contacts closed whilst the switch is held in position. Once the switch is let go, the current is broken and the switch turns off. Push switches are usually a simple on-off switch.