Relay (disambiguation)

A relay is an electric switch operated by a signal in one circuit to control another circuit.

Relay may also refer to:

Electrical engineering

 * Protective relay, a device designed to trip a circuit breaker when a fault is detected.

Historical

 * Stage station, a place where exhausted horses being used for transport could be exchanged for fresh ones
 * Cursus publicus, a courier service in the Roman Empire
 * Relay league, a chain of message-forwarding stations

Computer networking

 * BITNET Relay, a 1980s online chat system
 * Mail relay, a server used for forwarding e-mail
 * Open mail relay, such a server that can be used by anyone

Other telecommunication

 * Relay (satellite)
 * Broadcast relay station, a transmitter which repeats or transponds the signal of another
 * Microwave radio relay
 * Relay channel, in information theory, a communications probability modeling system
 * Telecommunications Relay Service, a telephone accessibility service for the deaf
 * Repeater, an electronic device that receives and retransmits a signal

Automobiles

 * Citroën Relay, a marketing name for the Fiat Ducato van
 * Saturn Relay, a 2005-2007 minivan

Other uses

 * Relay (shop), a France-based chain of convenience stores
 * Relay (company), a peer-to-peer political texting platform
 * "Relay" (song), 1972, by The Who
 * Relay bid, in contract bridge
 * Relay race, completed in parts by several participants of a team
 * Relay neuron, in anatomy
 * Relay box, a piece of postal infrastructure.