The Physics of the Vicsek Model

These are lecture notes on the Vicsek model for flocking that I prepared for the Microswimmers Summer School 2015 at Forschungszentrum J\"ulich. They give an essential introduction to this well known model, discussing its algorithmical implementation and the basic properties of its universality class. I present results from numerical simulations and insist on the role played by symmetries and conservation laws. Analytical arguments are presented in an accessible and simplified way, but ample references are given for more advanced readings.