Lecture notes on rational Cherednik algebras, Hecke algebras for varieties with group actions, twisted differential operators, some algebraic geometry preliminaries, the Cherednik algebra of a variety with a finite group action, globalization, modified Cherednik algebra, orbifold Hecke algebras, Hecke algebras attached to Fuchsian groups, Hecke algebras of wallpaper groups and del Pezzo surfaces, the Knizhnik-Zamolodchikov functor, the simplest case of double affine Hecke algebras, affine and extended affine Weyl groups, Cherednik’s double affine Hecke algebra of a root system, and algebraic flatness of Hecke algebras of polygonal Fuchsian groups.