In the realm of networking, relay systems are fundamental for the transfer of data packets across networks. Relays ensure that data can travel between different network segments, especially in complex environments where devices may not be directly connected. For example, in the case of email systems, mail relay servers forward messages between different mail servers, ensuring that emails reach their intended recipients even if they are across different domains.

    Relays also play a crucial role in long-distance communication, particularly in the context of satellite and radio communications. In such systems, relays are used to boost signals, ensuring they travel efficiently across vast distances without degradation.