This book elaborates the research work done to achieve better Quality of Service (QoS) in Internet using priority based schedulers. It introduces a Variable-Weighted Fair Queuing scheduling algorithm (V-WFQ) that provides Quality of Service by dynamically adapting packet priorities to varying network traffic congestion at each router, taking into account the priority of the service being provided.In Variable-Weighted Fair Queuing the changes in congestion at a router will be reflected in a change in the relative priority among flows. V- WFQ provides a prioritization scheme in which higher level Types of Service (ToS) flows dominate the network resources when network resources are constrained, leaving the lower level ToS flows with the remaining resources. This is accomplished through the altering of the flows relative priorities which is implemented with multiple forwarding queues that reflect the type of flow and the congestion level of the network.