A bhikkhu's life is governed in detail by the Vinaya, the monastic code attributed to rules the Buddha established over his lifetime in response to specific incidents of misconduct among his followers, preserved in somewhat differing but broadly overlapping versions across the various early Buddhist schools whose ordination lineages survive today. The Theravada Vinaya's patimokkha, the code's core list of rules recited communally on observance days, contains 227 rules for fully ordained monks, ranging from four offenses entailing automatic expulsion from the monastic community, sexual intercourse, theft, killing a human being, and falsely claiming spiritual attainment, down through numerous lesser rules governing everything from the handling of money and food to appropriate speech and dress, a graduated system of offense and remedy rather than a single uniform standard of discipline.
A bhikkhu traditionally owns only a small set of permitted possessions, most iconically the three robes and an alms bowl, and historically depended entirely on alms food gathered on a daily almsround through a nearby town or village, a practice still maintained in much of contemporary Theravada Southeast Asia and understood as serving a reciprocal function: the monk receives material sustenance while the lay donor gains religious merit through the act of giving, a relationship structuring lay-monastic interdependence across the Theravada world.