What type of documentation is necessary for international travel with Frontier Airlines?

When traveling internationally with Frontier Airlines, it is essential to have a valid passport as it serves as the primary form of identification that verifies your citizenship when entering another country. Additionally, depending on the destination, travelers may also need to secure specific visas in advance. These visas are required by some countries for entry and can dictate the duration of stay, the purpose of the visit, and more, based on the traveler's nationality and the nature of the trip.

The requirement for a passport and potential visas ensures compliance with international laws and regulations regarding border control and immigration. This is crucial not only for the traveler's legitimate entry into foreign countries but also for the airline's responsibility to ensure that passengers have the necessary documentation before boarding flights.

Other alternatives such as a driver's license and social security card are typically insufficient for international travel, as these forms of identification do not meet the international requirements set forth by border authorities. Additionally, traveling solely with a birth certificate would not satisfy the documentation requirements for international flights. Lastly, while there are cases where no documents are needed for travel within certain borders or regions (like domestic flights), this is not applicable for international travel.