The physics of gravitational waves

These lecture notes collect the material that I have been using over the years for various short courses on the physics of gravitational waves, first at the Institut d’Astrophysique de Paris (France), and then at SISSA (Italy) and various summer/winter schools. The level should be appropriate for PhD students in physics or for MSc students that have taken a first course in general relativity. The focus is on deriving results from first principles, rather than on astrophysical applications.