When checking in for a Frontier Airlines flight, passengers are generally required to present a valid form of identification. This is particularly important for travelers over the age of eighteen, as government-issued photo identification, such as a driver’s license or passport, is typically necessary. These identification requirements are in place to ensure security and verify the identity of passengers before they board the aircraft. It is also essential for minors to have proper identification as specified by Frontier Airlines, along with any additional documentation that may be necessary for unaccompanied minors or specific travel regulations. For the most accurate and up-to-date information regarding identification and travel requirements, it is recommended to check the current web page of Frontier Airlines.