The Cartesian product of two sets 
and 
(also called the product set,
set direct product, or cross product) is the set of all ordered pairs 
where 
and 
. It is denoted 
, and is called the Cartesian product since it originated
in Descartes' formulation of analytic geometry.
In the Cartesian view, points in the plane
are specified by their vertical and horizontal coordinates,
with points on a line being specified
by just one coordinate. The main examples of direct
products are Euclidean three-space (
, where 
are the real numbers), and
the plane (
).
The term Cartesian product is also used for the graph Cartesian product (Vizing 1963, Clark and Suen 2000).
