A passport is an official travel document issued by a government that contains a given person's identity. It enables its holder travel to and from foreign countries and to access consular assistance while overseas. The document certifies the personal identity and nationality of its holder.
The Transportation Security Administration (TSA) accepts the passport card as ID for domestic flights. Use the passport card when entering the United States at land-border crossings and sea ports-of-entry from Canada, Mexico, the Caribbean, and Bermuda. Do not use it for international air travel.