If you're applying for documents to travel outside of the United States of America, you may have noticed that you have two options: You can apply for either a passport book or a passport card.

Passport cards are cheaper than a passport book. Get both a passport book and a card if you travel by air and land equally.

For this reason, the Department of State recommends that anyone taking a cruise from the United States carry a valid passport book. Plus, the rules aren't cut and dry – some countries require a ...