This is the first of 3 planned lectures devoted to present selected works concerning the study of Giant Resonances (GR). The topic is very broad so that some basic concepts will be introduced in this first lecture/seminar. The case of the isoscalar giant monopole resonance will be discussed and will be the main subject of lecture 1. A short introduction to the giant dipole resonance will be also given. The topic of the electric dipole response at zero and at finite temperature will be treated in the next two lectures.