abstract: Hodge theory, as developed by Deligne and Griffiths, is an essential tool for analyzing the geometry and arithmetic of complex algebraic varieties. It is a crucial fact that at heart, Hodge theory is NOT algebraic. On the other hand, according to both the Hodge conjecture and the Grothendieck period conjecture, this transcendence is severely constrained. Tame geometry, whose idea was introduced by Grothendieck in the 80s, and developed by model theorists under the name "o-minimal geometry", seems a natural setting for understanding these constraints. In these lectures I will present a number of recent applications of tame geometry to several problems related to Hodge theory and periods.