Which technique is used by FASTag, as reported in the news recently?

The 'One Vehicle, One FASTag' initiative was recently launched by the National Highways Authority of India (NHAI) to encourage the use of RFID technology for toll payments. A vehicle-specific RFID passive tag called FASTag makes it possible to complete toll transactions while driving. Installed on the windshield, it takes toll money straight out of the associated current or savings/prepaid account. FASTag is available through National Electronic Toll Collection Member Banks and is not transferable between vehicles. Prepaid accounts need to be periodically recharged.