What is cross join in SQL

When two tables R1 and R2 every tuple of R1 gets combine every others tuple of R2.

R1(N1 tuple)*R2(N2 tuple)

N1*N2 number of tuple

Example

Output

A       B       C        C        D

X       10     100      100     L

X       10     100      200    M

Y       20     100      100     L

Y       20     100      200     M