This document discusses various concepts relating to functions, including: 1) It defines the types of functions - surjective, injective, and bijective - and provides examples to illustrate each type. 2) It covers algebraic operations that can be performed on functions, such as addition, subtraction, multiplication, and division, demonstrating each with an example. 3) It explains the concept of function composition, using examples to demonstrate what it means for one function to be composed with another (f o g). 4) It discusses the relationship between inverse and composition functions, proving that the identity function satisfies f o f^-1 = f^-1 o f = I(x).