http://www.tutorialspoint.com/sql/sql-cartesian-joins.htm

Cross join is the certasian product of two table

It produces the Cartesian product of the tables involved in the join. A cross join that does not have a WHERE clause The size of a result set is the no of rows in the 1st table multiplied by the no of rows in the 2nd table. Example: is when company wants to combine each product with a pricing table to analyze each product at each price.