QoS is called "quality of service" in English and "quality of service" in Chinese. QoS is a security mechanism of the network and a technology to solve the problems of network delay and congestion.

Under normal circumstances, if the network is only used for a specific application system and there is no time limit, it does not need QoS, such as Web applications or email settings. But it is necessary for critical applications and multimedia applications. When the network is overloaded or congested, QoS can ensure that important traffic is not delayed or discarded, and at the same time ensure the efficient operation of the network.