Minhagim and the authority of custom

Minhag ("custom") is a practice adopted by a community that acquires binding force, sometimes summed up in the adage "custom overrides law." The diversity of minhagim distinguishes the Ashkenazi, Sephardi, Italian and Yemenite rites. Medieval compilations such as the Sefer ha-Minhagim of the Maharil fixed local usages, whose study illuminates the history of communities.