I have found alot of information about how to solve and graph parametric equations, but what I want to know is, what is the point, or why do they exist at all? The way I have seen it explained is that both x and y are stated in terms of another "term", usually t. But if I can state x and y in terms of t, shouldn't I be able to state t in terms of x, and therefore y in terms of x, like we are used to with Cartesian coordinates? I read something on Wikipedia that described the parameter, t, something like this: "the speed of a car is akin to the dependent variable, and the gas pedal is the independent variable. Press the pedal, the car goes a certain speed. Change the mechanical linkages, and you have changed a parameter by which the dependent relates to the independent" Ok, so that sounds like, y = x in one setting, and changing the "parameters" would be like changing how y relates to x: like y = 2x. I'm having trouble actually articulating the question! So, what's the point? Why do they exist? What makes it any different than just using x to define the function(s)?