A traffic receiver gives you access to information about current traffic conditions from a broadcast service. Some GPS models can use data from a traffic receiver to help you avoid roads with heavy traffic congestion.
Garmin’s StreetPilot 2720 is one of the first GPS models capable of using real-time traffic data. Most GPS models still do not have this capability.
Traffic information serivces include RDS-TMC and XM NavTraffic.