When you are traveling outside the USA, you must have your passport with you. A passport issued by the US Department of State certifies you as a citizen of your country, when requesting permission to enter other countries.
If you have never been a possessor of a US passport or your last US passport has been expired for more than 12 years, or your recent US passport has been stolen, lost or damaged, then you must apply for a new US passport. If a person is applying for the first time, then he needs to do so in person.
International travel is considered a right that cannot be denied to any citizen. Even so, not very long ago, people who held views associated with communism, like Paul Robeson and W.E.B. Dubois, were denied a US passport. However, the U.S. Department of State cogently maintained that they have the right to screen people and revoke their passports if necessary. For the same reasons, US passports to Libya, Lebanon and Iraq are still denied.
In order to strengthen US security goals, biometric technology has been extended to US passports. This is done by including certain physical characteristics of the applicant, for example fingerprints or retina scans, and analyzing their distinguishing traits.
A contemporary US e-passport has been proposed which will be a unique combination of both tighter security features and a novel design. It will have a computer chip attached to it, containing important data. This design will capture the essence of hope and success for the citizens of the USA.