SpaceWire is a spacecraft on-board data-handling network which connects instruments to the mass-memory, data processors and control processors. SpaceWire is simple to implement and has some specific characteristics that help it support data-handling applications in space: high-speed, low-power, simplicity, relatively low implementation cost, and architectural flexibility making it ideal for many space missions. SpaceWire provides high-speed (2 Mbits/s to 200 Mbits/s), bi-directional, full-duplex data-links, which connect together SpaceWire-enabled equipment. Data-handling networks can be built to suit particular applications using point-to-point data-links and routing switches. SpaceWire is already in orbit or being designed into more than 100 spacecraft supporting Earth Observation, Science, Exploration, and Telecommunications missions. High-profile spacecraft using SpaceWire include: Gaia, ExoMars, Bepi-Colombo, Lunar Reconnaissance Orbiter, GOES-R, James Webb Space Telescope, and Astro-H.