The title of this article is ambiguous. For other meanings, see Space travel (disambiguation).

Space flight (also called space travel, cosmonautics, or astronautics) refers to travel or transportation to or through space. The transition between Earth and space is fluid, set by the US Air Force at a limiting altitude of 50 miles (~80 km) and by the Fédération Aéronautique Internationale (FAI) at a limiting altitude of 100 kilometers (for the latter, see Kármán line). Both defined altitudes are in the high atmosphere.

While the theory of space flight was developed as early as 1900 by Konstantin Eduardovich Tsiolkovsky with the formulation of the rocket equations, the first solid rockets had been around for many centuries. The first liquid-propellant rockets were developed from the 1920s by Robert Goddard and, in the context of the Second World War, by Wernher von Braun.

The start of practical spaceflight is considered to be the launch of Sputnik 1 by the Soviet Union on October 4, 1957. Milestones of manned spaceflight included Vostok 1 with Yuri Gagarin in 1961 as the first human in space, the first manned moon landing with Apollo 11 in 1969, the first manned space station with Salyut 1 in 1971, or the first reusable spacecraft with the space shuttle in 1981. By the end of 2017, more than 500 people had been in space (see list of space travelers). In unmanned spaceflight, space probes have explored the Moon and planets. In large numbers, communications satellites operate at geostationary positions. Navigation satellites orbit the Earth so that multiple satellites can be received from any location on Earth, if possible. Earth observation satellites provide high-resolution images for commercial and military purposes.