Quality of service gauges the overall performance of different services within the network in many applications like voice telephony, video conferencing, audio conferencing etc. This paper involves the analysis of quality of service among different application by using Opnet workbench. With the help of Opnet which includes many built-in parameters thus by using some parameters of QoS within an Opnet, the effect of QoS has been detected. The central idea is to mainly determine the role of QoS on some applications. This paper includes a simple network which does not include quality of service and a complete network with some applications in which authentic parameters regarding the quality of service, are applied. Thus, it has been concluded there is a great impact of QoS in a network. A network without quality is considered to be a poor network so this paper majorly emphasizes the importance of QoS.