Abstract: In this talk, we discuss regularity properties of minimal segregated configurations, defined as vector valued functions with the property that, for each point in the domain, at most one component is non-zero, and that minimize the corresponding Dirichlet energy. We first introduce the topic, emphasizing the connections with shape optimization problems (optimal partitions) and harmonic maps with values into singular spaces. Then, we introduce the notion of free boundary, we review some known results about its regularity and geometrical structure (mainly focusing on the seminal works by Gromov-Schoen, Conti-Terracini-Verzini and Caffarelli-Lin) and we finally describe recent results obtained in collaboration with B. Velichkov.