The primary purpose of a passport is to serve as an official document that certifies a person's identity and nationality for international travel. Issued by a government, a passport allows individuals to cross international borders and return to their home country. It typically contains personal information such as the individual’s name, date of birth, and a photograph. Additionally, passports may include visa pages for travelers to obtain entry permissions for foreign countries, facilitating international relations and travel security by providing a standardized form of identification.