Friends of society
A "friends of" is type of not-for-profit society created solely to support some other organization or enterprise, typically through fundraising, lobbying, and publicity. They are very common in the galleries, libraries, archives, and museums (GLAM) sector. They have a long history going back to the 19th century, particularly in Western Europe. The first know friends of a museum society is the Vorarlberger Landesmuseumverein of Austria, set up in 1857. Other early examples include the 
Société des amis des monuments parisiens ("Friends of Parisien Monuments", 1885), the Société des amis des monuments rouennais ("Friends of Rouennais Monuments", founded 1886), and the Société des amis du Louvre ("Friends of the Louvre", founded 1897), the later of which became so popular that it has an American counterpart, the American Friends of the Louvre, based in New York.