Before you use software, you need to understand some basic concepts and assumptions of queuing theory. A queuing system consists of three components: the arrival process, the service process, and the queue discipline. The arrival process describes how customers or tasks arrive at the system, such as randomly, periodically, or in batches. The service process describes how the system serves the customers or tasks, such as how long it takes, how many servers are available, and how they are allocated. The queue discipline describes how the customers or tasks are ordered in the waiting line, such as first-come first-served, last-come first-served, or priority-based. Queuing theory uses mathematical models and formulas to analyze these components and measure the performance of the system, such as the average waiting time, the average queue length, the utilization rate, and the probability of blocking or loss.