Abstract: This chapter gives a thorough treatment of minimal types and other types such as indiscernible, end-extensional, rare, and selective types. Their connections with each other are discussed. How types are used to produce elementary extensions is examined, and an introduction to automorphism groups and substructure lattices is provided. The chapter ends with proofs of the two Paris-Mills theorems.

Keywords: indiscernible types, end-extensional types, rare types, selective types, resolute types, Paris-Mills theorems,