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  • Dustin Waybright thinks this is interesting:

If you have m rows in table T1 and n rows in table T2, the result of a cross join between T1 and T2 is a virtual table with m x n rows.

From

Cover of Training Kit (Exam 70-461): Querying Microsoft® SQL Server® 2012

Note

The CROSS JOIN does not use a key. It takes every row from 1 table replicates it with every value from the other table.