A passport is a travel document, usually issued by a country's government, that certifies the identity and nationality of its holder primarily for the purpose of international travel. Standard passports may contain information such as the holder's name, place and date of birth, photograph, signature, and other identifying information. Many countries are moving towards including biometric information in a microchip embedded in the passport, making them machine-readable and difficult to counterfeit. As of 2017, there are over 120 jurisdictions issuing these e-Passports. Previously issued passports usually remain valid until each expires.