According to Delta Airlines, as of September 2010, passports are required for anyone participating in international travel. A passport's function is to prove a person's identity and legal citizenship of one country before receiving permission to enter another country.
A visa is a document issued by the embassy of another country, its purpose being to give permission to a traveler to enter the border. According to the U.S. Department of State, the kind of visa needed depends on the reason for the person's travel.
The rules and regulations for visas and passports vary from country to country, and it is imperative that an individual ascertain the precise regulations associated with the country he is planning to visit. Country-specific information can be found on the U.S. Department of State's website.
