This is the first talk of the dynamics working group on May 24th. It serves as an introduction to the mini course of canonical height function (a.k.a. projective height). We will spend most of the time on this session to give enough background to the audience by introducing several preliminaries, such as places, extension of absolute values to a number field, local degree, embeddings, etc. Then, we will give several equivalence definitions of canonical height. In general, the projective height is defined over an $n$-dimensional projective space. However, one could also define it over a finite product of projective spaces, which motivates the notion of Zhang-Zagier height. Both views lead us to focus on the paper by D.Zagier published in 1993, namely ‘‘Algebraic Numbers Close to Both \(0\) and \(1\)’’. I will breifly introduce the paper, using the lemmas to prove the theorems. If we still have time, I will pick some part of the paper to give more details. No number theory/algebraic geometry backgroud is required.