Flightradar24, the site tracking every plane in the sky

(CNN) — On an average day, more than 200,000 flights take off and land across the world. That includes commercial, cargo and charter planes — which account for about half of the total — as well as business jets, private aircraft, helicopters, air ambulances, government and military aircraft, drones, hot air balloons and gliders.

Most of them are equipped with a transponder, a device that communicates the aircraft’s position and other flight data to air traffic control, and that signal can be captured with inexpensive receivers based on a technology called ADS-B, for Automatic Dependent Surveillance-Broadcast. That’s what flight-tracking websites do in a nutshell, providing users with a real-time snapshot of everything that’s in the sky (minus a few exceptions).

The plane, a military version of the Boeing 737 called C-40, departed from Kuala Lumpur in Malaysia before embarking on a circuitous path to Taiwan, in order to avoid encounters with the Chinese military, adding hours of flight time. That didn’t make it immediately obvious what the final destination would be, sparking online conversations as the plane slowly veered north towards the island. As a result, it was the most tracked flight of all time on Flightradar24, with 2.92 million people following at least a portion of the seven-hour journey.

The website, part of a group of popular flight-tracking services along with FlightAware and Plane Finder, was founded in Sweden in 2006 “completely by accident,” says FlightRadar24’s director of communications, Ian Petchenik, as a way to drive traffic to a flight price comparison service.

Interest on the rise

Before Pelosi’s flight, the record for the most tracked…