What is the difference between domain & range?

The variable along the X-axis is the domain and the variable along the Y-axis is the range.

is this part of a question or something

sample answer: you can determine whether each element of the domain is paired with exactly one element of the range. for example, if given a graph, you could use the vertical line test; if a vertical line intersects the graph more than once, then the relation that the graph represents is not a function.