The lof, also known as caví, is the fundamental social organization for the Mapuche, Mapuche-Huilliche, and extinct Picunche peoples. It functions as a familial clan or lineage that recognizes the authority of a leader known as a lonco (cacique).
A lof is composed of diverse families who share the same territory and are considered mutually related through descent from a common ancestor. These units form larger structures, where several lof constitute a rehue, and nine rehue combine to form an aillarehue. These groupings ultimately comprise one of the great territorial confederations of the Mapuches, known as the Butalmapu.