Frontier Airlines is a low-cost airline based in the United States. It is headquartered in Denver, Colorado. The airline operates flights to over 100 destinations within the United States, Mexico, Canada, and the Dominican Republic. Frontier Airlines is known for its affordable fares and its "ultra-low-cost carrier" business model, which charges extra fees for services such as seat selection and carry-on bags. Despite being a budget airline, Frontier Airlines offers a range of amenities on board, including in-flight entertainment and refreshments for purchase.