Spacecraft, or spaceships, are vehicles designed for travel or operation in outer space. They vary in size and purpose, from small satellites and probes to massive crewed spacecraft like the International Space Station and future missions to the Moon and Mars. Spacecraft use various propulsion systems, such as chemical rockets, ion drives, and solar sails, to maneuver through space. They play a crucial role in exploring the cosmos, conducting scientific research, and supporting human activities beyond Earth.