The Betti map is a certain multivalued real-analytic map attached to sections of abelian schemes, which has arisen in Diophantine Geometry in many guises. It has now become a fundamental tool in the domain of « unlikely intersections », as well as, later, in « uniformity questions » about rational points. The talk will survey this notion, its origins, some of its applications, and its link with more standard notions such as the Kodaira-Spencer map.