# Kinds Of Functions

1. One-to-one Function (or injective function)
A function f  is called one-one mapping if every distinct element of A has a distinct image in B.
Thus, a function f  is one-one
2. Many-one Function : A function f :  is many-one if two or more different elements of A have the same image in B.
Thus, f :  is many-one if
3. Onto or Surjective Function : The function f :  is said to be an onto function if every element of B is image of at least one element of A.
For a surjective function f,
Range of f = co-domain (B)
4. Into Function : If the function f  is such that there is at least one element of B which is not the image of any element of A, then f is called an into function.
For an into function f.
Range of f  co-domain (B)

Bijective function :
A function f :  is a bijective function if f is one-one as well as onto, i.e. f is injective and surjective both.