Help with Foreign Keys

[eluser]orokusaki[/eluser]
Thanks a lot for all the great replies guys. I love the community here. I do have one more question though. I know I said no code was needed, and it's really not still, but I am still a little confused about the implementation of foreign keys.

How do you use them. Do they work automatically. Do two tables that reference each other delete columns at the same time like a DB transaction, or do you still have to do the programmatic legwork, and they just prevent you from completing the transaction unless all connected data is deleted. Do you have to use JOIN?

By the way, is JOIN the sort-of other way of doing foreign key databases without using foreign keys.