A push button is a simple type of switch that controls an action in a machine or some type of process. Most of the time, the buttons are plastic or metal. The shape of the push button may conform to fingers or hands for easy use, or they may simply be flat. 

Push button switches typically have two key parts, an actuator and the contacts. The actuator will go all the way through the switch and into a thin cylinder at the bottom. Inside is a movable contact and spring. When the actuator is pressed, it touches with the stationary contacts, causing the action to take place. 

Push buttons are available with normally open or normally closed contacts that change state when the actuator is operated. Momentary switches require the user to keep holding the button for an action to take place, this action is then reset once the button is released. Latching push buttons keep the switch in the set contact state until the button is pressed again.

Push button switches are popular in a variety of different applications, including calculators, push button phones, and many home appliances. You can find them in the home, the office, and in industrial applications. They can turn machines on and off, or cause the devices to perform specific actions, as is the case with calculators. In some cases, specifically for commercial and industrial usage, the buttons can connect through mechanical linkage, which means that pushing one button can actually cause another button to release.

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