A passport book number is a unique number assigned to each passport holder. It consists of nine digits, which are divided into two parts. The first part consists of two letters followed by seven ...

When booking travel, you'll sometimes need to enter your passport number. Here's how you can look up your passport number if you don't have it on hand.

You don’t need a passport number to book an international flight. However, make sure to leave enough time for a passport renewal or a new application because it can take a while to process.

Passport book: Allows international travel by air, sea, or land to any country. Required for air travel outside the U.S. Larger in size (booklet format) with pages for visas and stamps.