The Space Age is a period encompassing the activities related to the space race, space exploration, space technology, and the cultural developments influenced by these events, beginning with the launch of Sputnik 1 on October 4, 1957, ending with the completion Apollo-Soyuz Test Project that marked the conclusion of the Space Race in 1975.

The Space Age is characterized by changes in emphasis on particular areas of space exploration and applications. Initially, the United States and the Soviet Union invested unprecedented amounts of resources in breaking records and being first to meet milestones in crewed and uncrewed exploration. The United States established the National Aeronautics and Space Administration (NASA) and the USSR established the Kosmicheskaya programma SSSR to meet these goals. This period of competition gave way to cooperation between those nations and emphasis on scientific research and commercial applications of space-based technology.

Eventually other nations became spacefaring. They formed organizations such as the European Space Agency (ESA), the Japan Aerospace Exploration Agency (JAXA), the Indian Space Research Organization (ISRO), and the China National Space Administration (CNSA). When the USSR dissolved the Russian Federation continued their program as Roscosmos.

In the early 2020s, some journalists have used the phrase "New Space Age" in reference to a resurgence of innovation and public interest in space exploration as well as commercial applications of low Earth orbit (LEO) and more distant destinations. New developments include the participation of billionaires in crewed space travel, including space tourism and interplanetary travel.

The periodization of the Space Age can differ substantially, with some differentiating between a first Space Age and a second Space Age, which are separated at the turn of the 1980s/1990s.

Some vehicles reached suborbital space much earlier than the launch of Sputnik. In June 1944, a German V-2 rocket became the first manmade object to enter space, albeit only briefly. In March 1926 American rocket pioneer Robert H. Goddard launched the world's first liquid fuel rocket. This was considered by some to be the start of the Space Age, although it did not reach outer space.

Since Germans undertook the sub-orbital V-2 rocket flight in secrecy, it was not initially public knowledge. Also, the German launches, as well as the subsequent sounding rocket tests performed in both the United States and the Soviet Union during the late 1940s and early 1950s, were not considered significant enough to define the start of the space age because they did not reach orbit. A rocket powerful enough to reach orbit could also be used as an intercontinental ballistic missile, that could deliver a warhead to any location on Earth. Some commentators claim this is why the orbital standard is commonly used to define when the space age began.

The Space Race was the first era of the Space Age. It was a race between the United States and the Soviet Union which began with the Soviet Union's October 4, 1957, launch of Earth's first artificial satellite Sputnik 1 during the International Geophysical Year. Weighing 83.6 kg (184.3 lb) and orbiting the Earth once every 98 minutes. The race resulted in rapid advances in rocketry, materials science, and other areas. One of the underlying motivations for the space race was military. The two nations were also in a nuclear arms race following the Second World War. Both nations made use of German missile technology and scientists from their missile program. The advantages, in aviation and rocketry, required for delivery systems were seen as necessary for national security and political superiority.