A Relay are electro-mechanical switch that uses electrical signal to control an electromagnet, which in turn connects or disconnects another circuit. Electro-mechanical relays and solid state relays are the most commonly used relays in electronic / electrical circuits.

Relays can switch one or more circuits. Each switch in relay is referred as pole. Number of circuits a relay connects is indicated by throws. Based on poles and throws, relays can be classified as 'Single Pole Single Throw' (SPST) type, 'Single Pole Double Throw' (SPDT) type, 'Double Pole Single Throw' (DPST) type, 'Double Pole Double Throw' (DPDT) type, etc. There are relays with more poles also.

Relays come with different voltage current ratings for switching signals or pole interconnection. Relays also come in various sizes and form factors.

In this section we have listed many popular relay types from reputed brands to cater to specific electronic projects.