Mobile Check-In is a convenient feature that allows travelers to check in for their flights using a smartphone or tablet. Instead of waiting in long lines at the airport, passengers can complete the check-in process from anywhere, often starting 24 hours before their flight. This process typically involves entering booking details and selecting seats. Once checked in, travelers can receive their boarding passes digitally, which can be saved on their devices or sent via email. Many airlines, such as Delta and American Airlines, offer mobile apps that streamline this process, making air travel more efficient and user-friendly.