The Kathina is the annual ceremony, held in the month after the end of the three-month rains retreat (vassa), at which lay supporters offer cloth for robes to a community of monks who have kept the retreat together. It is the one great occasion of communal giving in the Theravada monastic year, and its rules are set out in the Vinaya, the monastic code: the offered cloth is formally received by the assembled community and made up, sometimes within a single day, into a robe that is then conferred by the monks upon one of their number.
For the lay donors the occasion is a chief opportunity to make merit; for the monks who have completed the retreat it brings certain relaxations of the disciplinary rules for a period. The ceremony can be held by a given monastery only once a year and only after a valid rains retreat, which gives it a particular importance in the life of a Theravada community across Sri Lanka and Southeast Asia.