Symmetries of spaces and numbers -- anabelian geometry

Abstract: ``Can number and geometric spaces be reconstructed from their symmetries?'' This question, which is at the heart of anabelian geometry, a theory built on the collaborative efforts of an international community in many variants and with the Japanese arithmetic school as a core, illustrates, in the case of a positive answer, the universality of the homotopic method in arithmetic geometry. Starting with elementary examples, we first introduce the motivations and guiding principles of the theory, then present its most structuring results and its contemporary trends. As a result, the reader is presented with a rich and diverse landscape of mathematics, which thrives on theoretical and explicit methods, and runs from number theory to topology.