In mathematics, a function is a binary relation between two sets that associates every element of the first set to exactly one element of the second set. Typical examples are functions from integers to integers, or from the real numbers to real numbers. A functioning rule describes how to convert an input value (x) into an output value (y) for a given function. An example of a function rule is f(x) = x^2 + 3. In other words, a function f is a relation such that no two pairs in the relation have the first element. Here, in this chapter, students are taught about different Functions and how some real standard functions are represented on graphs.