I will recall some results on (complex) representation theory of finite groups, with a focus on symmetric groups. Namely, there is a natural probability measure defined on the set of irreducible representations. We will then study the p-regularisation map on partitions, which was introduced by James in order to study the representations of the symmetric group when the ground field has characteristic p. Based on a limit shape result of Kerov–Vershik and Logan-Shepp, we will study the shape of the p-regularisation of a large random partition. Finally, we will mention a generalisation of the p-regularisation map, defined by Diego Millan Berdasco.