A process flow diagram is a type of flow chart that is used to visualize the steps of a process. It is one of the most common types of diagrams used in business and engineering. The process flow diagram cyclic describes how a product or service moves from one step to another, and then back again. The main purpose of this type of diagram is to show the sequence in which a particular product or service goes through each step during its life cycle. A typical example would be an automobile manufacturing company that sells its cars through dealerships. A dealership will buy cars in bulk, sell them, and then purchase new cars for resale. This process would have four steps: buying, selling, reselling, and buying again.