Flightradar24 is a global flight tracking service that provides real-time information about thousands of aircraft around the world. It combines data from multiple sources, including ADS-B receivers, radar data, and flight schedules, to display the current location, altitude, speed, and other details of flights on a map. Users can search for specific flights, airports, or regions, and view historical flight data. It is used to track flights and get detailed information about air traffic.