Resumo: Associative submanifolds are special 3-dimensional manifolds in manifolds which are 7-dimensional. They are examples of calibrated submanifolds and there is a research programme that attempts to count them in order to define numerical invariants of manifolds, similar to Gromov-Witten invariants. However the scarcity of examples of associative submanifolds makes it difficult to work out the details of this programme. In the talk I will explain how to construct associatives in manifolds constructed by Joyce, whose existence had previously been predicted by physicists. The talk is based on a joint work with Daniel Platt (King's College London) and Thomas Walpuski (Humboldt University, Berlin).