In Star Trek, what communication technology allows messages to travel faster than light?

In Star Trek, subspace communications allow messages to travel faster than light.

Starfleet ships use subspace transmissions to exchange voice, video, and data across interstellar distances without waiting for ordinary light-speed signals. The technology depends on subspace, a fictional medium or domain that permits faster-than-light effects while remaining distinct from normal space.

Subspace communications are central to the setting because they let starships stay in contact with Starfleet Command, nearby vessels, and distant colonies. Communication range and speed are not always consistent in the stories, and interference, subspace storms, distance, or damaged equipment can disrupt a signal.

Subspace communication should not be confused with warp drive, which propels a vessel, or with a transporter, which transfers matter. It is also distinct from the ship’s ordinary radio systems: the key feature of a subspace transmission is its faster-than-light capability. Different Star Trek series depict the equipment and terminology in slightly different ways.