[Tomvart]

Another fascinating resource Sparkie, many thanks thanks for posting (and finding!), this geek found it quite immersive and consequently its now bookmarked for future reference!

Looks like it uses a number of data sources (most of them ATC Datalinks):
ADS-B Auto Dependent Surveillance–Broadcast (using UHF IFF mode 5 Transponder system),
ADS-C Auto Dependent Surveillance–Contract (using SATCOM).
ADS-R Auto Dependent Surveillance–Rebroadcast
UAT - Universal Access Transceiver (used for ADS-R retransmissions of ADS-B/C, TIS and FIS data)
MLAT - Multilateration
TIS-B - Traffic Information Service-Broadcast
FIS-B - Fight Information System-Broadcast (Weather and Airspace restrictions)

ADS-B is essentially an open UHF broadcast of information pertaining to an individual aircraft giving its own location, altitude, speed, type and callsign with an update rate of around 1 second using UHF IFF Mode 5 Transponder system.

ADS-C is similar to ADS-B but is for aircraft under control - normally used on long 'over ocean' flights (C='Contract' - between the ATC controller and the controlled aircraft), transmissions are under the direction of the ground controller with an average update rate of 10 minutes using SATCOM.

MLAT = Multilateration, this ground based system calculates the position of aircraft in the vicinity of airfields by computing the Time Difference Of Arrival (TDOA) of the received signals from the IFF modes S, A, C, and transponders on board the aircraft (UHF band).