A relay satellite is a type of artificial satellite that is designed to receive and retransmit signals between two or more points on Earth, or between a point on Earth and a spacecraft in space. There are several synonyms for the term "relay satellite", including communication satellite, communications relay satellite, signal relay satellite, and transponder satellite. These terms are often used interchangeably to refer to a satellite that is used for telecommunications or data transmission purposes. Relay satellites are an important part of modern communications infrastructure, facilitating data transfer for everything from telephone conversations to television broadcasts. They allow for faster, more reliable communication across long distances, making them a cornerstone of modern society.