The range of a function is the set of all possible output values (y-values) that the function can produce.
The domain of a function is the set of all possible input values (x-values) for which the function is defined.
A mathematical relationship between two sets, where each input value corresponds to exactly one output value.
Vertical Line Test: A test used to determine if a graph represents a valid function by checking if any vertical line intersects it more than once.