The United Federation of Planets serves as the fulcrum for the Star Trek franchise, a utopian future society in which science and enlightenment have triumphed. It consists of hundreds of member worlds who share knowledge and resources for the mutual benefit of all. Starfleet serves as its diplomatic corps and defense force, as well as exploring unknown space in its name.
Source:https://www.cbr.com/star-trek-how-old-is-federation/