Parametric functions describe how two or more quantities change together as they depend on a third variable, called a parameter. Instead of writing one variable directly in terms of another, like y = f(x), we express both x and y in terms of a separate variable t. For example, x = f(t) and y = g(t). As t changes, the pair (x, y) moves along a path, forming a curve. This method is useful because it can represent shapes and motions that are hard to describe with a single equation, such as circles,