Mechanical switches are one of the most common electrical devices as they allow power to be turned on or off.
Switches are rated for the amount of current and voltage they are suitable for. For switching low power and low currents like using a switch as an input to a microcontroller just about any switch will do. When using a switch to control power from a battery or turn a motor on then care should be taken to ensure the switch is rated to the expected current. For high power uses an electronic solid state switch can be better.
Mechanically switches are varied. Momentary switches are either on or off while you hold them like buttons while others will maintain the state until switched back like toggles or sliders. Like relays, switches can be SPST (single pole single throw), DPDT (double pole double throw) or lots of other variations.
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