A correspondence plot represents the results of correspondence analysis (CA). For each category (possible value of a variable), its scores derived by CA for the first two dimensions are depicted as a point on the x-y plane.
An interesting feature of the correspondence plot is that two variables, radically different in their nature, still may be represented simultaneously on the same plot (usually contrasted by color or the mark shape). Besides showing the relation between the values of the same variable, the correspondence plot shows the relation between a value of one variable and a value of another variable.
Because of this ability to represent values (categories) of two variables simultaneously, this sort of plots are often called biplots.