Communitarianism is the idea that interests of society should be put above interests of the individual. It is not the same as collectivism, as it does not advocate forcibly restraining the rights of individual.
Communitarian philosophies have existed in some form since the beginning of human civilization, but the specific form which is relevant today originated in 1971 with John Rawls' book, Theory of Justice. Other inspirations were Ferdinand Tönnies, Amitai Etzioni and Dorothy Day. All of them aimed at a balance between liberal individualism and community spirit, often claiming that noone can fully express their individuality without living in a healthy community.
Communitarian thinking has influenced both leftist and neoconservative politics.
Similar concepts include 19th century Russian philosophy of Sobornost and Olaf Stapledon's personality-in-community.