Additional services or products offered by airlines to enhance the overall travel experience for passengers. These services are typically optional and come at an extra cost beyond the base fare. Ancillary services can include a wide range of offerings, such as seat selection, extra baggage allowance, in-flight meals, priority boarding, Wi-Fi access, travel insurance, lounge access, and more. Airlines often provide ancillary services as a way to generate additional revenue and cater to individual passenger preferences.