SMD Buttons

A button is a contact switch. When it's pressed, both ends of the circuit are connected. The schematic diagram of a button is as follows:

The below figure demonstrates a circuit switching on a LED when the button is pressed:

Explanation

  1. When the button is not pressed, the LED is not connected to GND, so it is turned off.
  2. When the button is pressed, there is a close loop for the circuit, therefore the LED is turned on.