Stefan Banach published his doctoral dissertation, “On operations on abstract sets and their applications to integral equations” in Fundamenta Mathematicae in 1922 [1]. The Banach Fixed Point Theorem or Banach Contraction Principle was one of them. Of the many Banach theorems, it is considered one of the most famous. It defines conditions for the existence and uniqueness of a fixed point of certain mappings (called contractions) of a complete metric space into itself. Banach’s fundamental fixed point theorem on a complete metric space is the origin of the metric fixed point theory. This chapter will present its main generalizations, contractive conditions, simpler proof and converse theorems. It is impossible to give all the information about the Banach Fixed Point Theorem that has been written in the past years since its publication. So, we are only highlighting the key milestones in the “metric fixed point theory”.