Relay means to pass something along from one person or place to another. When you relay a message, you're delivering it to someone on behalf of someone else, like when your teacher asks you to relay instructions to the office. A relay race works the same way: runners take turns carrying a baton around the track, each one passing it to the next teammate.

The word suggests a chain of connection, where something moves through multiple stages or people rather than going directly from start to finish. In the old days, messages were relayed across long distances by riders on horseback stationed at regular intervals, each carrying the message to the next rider. Today, TV networks relay signals from station to station so you can watch shows at home.

A relay can also be the thing itself: the race where teammates take turns, or an electrical device that passes signals through a circuit. When spacecraft communicate with Earth, their signals often bounce through relay satellites orbiting above us. The core idea stays the same: something travels in stages, with each link in the chain doing its part to move it forward.