A parametric equation defines a group of quantities as functions of one or more independent variables called parameters. Parametric equations are commonly used to express the coordinates of the points that make up a geometric object such as a curve or surface, in which case the equations are collectively called a parametric representation or parameterization (alternatively spelled as parametrisation) of the object. Mathematica has a dedicated command for these purposes: ParametricPlot.
As it can be seen, you can practically display any implicit function using the implicitplot command. Explicitly defined functions can be plotted using the regular plot command.