# Functions

__Types of Functions__

**One-on-one or Injective:** A function *f : A → B *is called one – to – one or injective if each element of B is the image of at most one element of A

**Onto or Surjective:** A function *f : A → B *is called onto or Surjective if every element of B is the image of some element of A.

**One – To – one Correspondence or Bijective:** A function *f : A → B *is said to be a one – to – one correspondence, or Bijective, or a bijection, if it is one – to – one and onto at the same time.

Find out more about functions by reading the explanation below.

**Practice:** Answer the following exercises about functions.