What is Quality of Service (QoS) really? It impacts the network and the business. It promises the ability to offer new revenue generating services. But QoS is not a panacea. To offer QoS services, more than just the DOCSIS network will need to be upgraded to QoS technology. The specific QoS technology is not so important as knowing why and where QoS should be deployed in the first place. This talk defines what QoS is, and then how an operator can use it in the network.