A biometric passport (also known as an electronic passport, electronic passport or digital passport) is a traditional passport that has a built-in electronic microprocessor chip that contains biometric information that can be used to authenticate the identity of the passport holder. It uses contactless smart card technology, which includes a microprocessor chip (computer chip) and an antenna (for both chip and communication) embedded on the front or back of the passport. Critical passport information is printed on the passport data page and stored on the chip. Public Key Infrastructure (PKI) is used to authenticate electronically stored data on the passport chip, making it expensive and difficult to forge when all security mechanisms are implemented fully and correctly. Many countries are moving towards the issue of biometric passports. As of December 2008, 60 countries issued these passports, and this number was 96 to 5 April 2017.