High Power Laser Matter Interaction A self contained introduction to the main aspects of high power laser matter interaction in the intensity range 10^10 10^22 W cm^2 from plasma formation to highly relativistic interactions of the laser field with matter is presented. It is intended as a guide for scientists and students who have just discovered the field as a new and attractive area of research and for scientists who have worked in another field and want to join now the subject of laser plasmas. In the first chapter the plasma dynamics is described phenomenologically by a two fluid model and similarity relations from dimensio