Every new body style of Civic is called a Generation...

73-78 is 1st Generation Civic (I THINK)
79-83 is 2nd Gen Civic (I THINK)
84-87 is 3rd Gen Civic or 1st Gen CRX
88-91 is 4th Gen Civic or 2nd Gen CRX
92-95 is 5th Gen Civic
96-00 is 6th Gen Civic
01-Current is 7th Gen Civic

I'll edit it if that is the wrong years.