Enhancements specified by Provider Backbone Bridging (PBB) address key deficiencies in traditional enterprise Ethernet, which has hindered its adoption as a carrier protocol. Ethernet interfaces and Ethernet-based services are already established and widely deployed, but Ethernet as a transport technology has lacked the key carrier grade features that Traffic-Engineered Provider Backbone Bridging (PBB-TE) now provides. This paper provides an overview of PBB-TE, explaining how the technology addresses the needs of carrier transport networks.