Cruise Credits are points that determine your Crown and Anchor status. The more Cruise Credits you have, the more benefits you'll receive. You earn 1 Cruise Credit after completing a 3 to 11 night cruise. You will earn 2 Cruise Credits if you complete a 12 night or more cruise. You will also receive 1 Cruise Credit if you are in a suite.
You are a Gold Member from 1 to 4 cruises. After you complete your 5th cruise you will be a Platium Member. After your 10th cruise you'll become a Diamond Member (this is when you really get the perks). After 24 completed cruises, you become a Diamond Plus Member.