Given two sets 
and 
, the Cartesian product, also known as the cross product or even just product, is written as 
, which is read as “A cross B.” It is the set of all ordered pairs 
where 
and 
.
When a set is crossed with itself one or more times it is written 
. For example, 
is usually written instead of 
.
Euclidean three-space, 
, is a very common Cartesian product.