If you like buying in bulk and saving money doing it, this is the place for you. Costco is a membership warehouse club dedicated to bringing the best prices on brand name merchandise.
To start up a membership, all you have to do is be the age of 18 or older, provide a valid US license or Identification, and pay $50 to start up. The memberships only last 12 months, so you have to keep renewing your regitration. My wife and I got a the gold membership which is the most standard one to get because we don't need all the extra hassle with upgrades. We just go in and shop what we need. For that membership, we were allowed 2 Costco photo ID cards (one for me and one for my wife). Not only that, they sent us $20 back in the mail for our first time signing up and free item coupons to use.