The European Space Agency (ESA; French: Agence spatiale europenne pronunciation , ASE; German: Europische Weltraumorganisation) is an intergovernmental organisation of 22 member states dedicated to the exploration of space. Established in 1975 and headquartered in Paris, ESA has a worldwide staff of about 2,200 in 2018 and an annual budget of about 7.2 billion in 2022.ESA's space flight programme includes human spaceflight (mainly through participation in the International Space Station program); the launch and operation of unmanned exploration missions to other planets and the Moon; Earth observation, science and telecommunication; designing launch vehicles; and maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana. The main European launch vehicle Ariane 5 is operated through Arianespace with ESA sharing in the costs of launching and further developing this launch vehicle. The agency is also working with NASA to manufacture the Orion spacecraft service module that will fly on the Space Launch System.

The European Space Research Organisation (ESRO) was an international organisation founded by 10 European nations with the intention of jointly pursuing scientific research in space. It was founded in 1964. As an organisation ESRO was based on a previously existing international scientific institution, CERN. The ESRO convention, the organisations founding document outlines it as an entity exclusively devoted to scientific pursuits. This was the case for most of its lifetime but in the final years before the formation of ESA, the European Space Agency, ESRO began a programme in the field of telecommunications. Consequently, ESA is not a mainly pure science focused entity but concentrates on telecommunications, earth observation and other application motivated activities. ESRO was merged with ELDO in 1975 to form the European Space Agency.