U.S. passports issued to individuals 16 or older are valid for 10 years, according to the U.S. State Department, while those issued to individuals younger than 16 expire after five years. U.S. passports show the expiration date on the page with the holder's photo.
Globally, passport validity varies by country, explains Wikipedia. As of 2015, 97 countries issue an adult passport that is good for 10 years; 13 issue passports for between five and 10 years; and 81 issue passports for fewer than five years. While most countries issue passports with a standard term, some countries allow applicants to choose a validity period. Some also offer elderly citizens passports that do not expire.