ABSTRACT: Eighty years ago, Ramanujan  discovered some beautiful congruences for the
ordinary partition function (the partition function p(n) denotes the number of ways to write n as the sum of a non-increasing sequence of positive integers).

From Ramanujan's time until very recently,  only a few further such congruences had been found.
In recent joint work with Ken Ono, we show that such congruences are much more common than was previously known.  Our results, which rely on the theory of modular forms, provide a theoretical
framework which explains every known partition function congruence.