# In this Section:

In this section, we introduce the concept of a function. We begin by learning the definition of a relation. A relation is simply any set of ordered pairs.
When a relation satisfies a certain criteria, it is known as a function. All functions are relations, but not all relations are functions. In order to have a function, each x value or
member of the domain has to correspond or be linked to exactly one y value or member of the range. As an example, suppose we looked at the following relation: {(0,3), (2,5), (6,11)}:
In this example, each x value corresponds to exactly one y value and we can say this relation represents a function.