The performance of any application is dependent on how much it gets or experiences in the way of bandwidth, delay, jitter and packet loss. Therefore, in QoS, the goal is to manage each of these conditions and proactively allocate them to each application (or session) based on its priority. The priority, of course, will be based on the application's importance to the company's business. Presumably, a mission-critical application is more important than Web surfing, and therefore must be allocated higher priority, just as VoIP traffic must be guaranteed bandwidth because a voice connection can be annoyingly poor or even completely incomprehensible if it is subjected to too much delay, jitter, or packet loss
