Assembly line is a group of work areas, called stations, arranged in a certain order to make a product. Each station performs a given task on a unit of a product--such as inserting, tightening, or inspecting a part--and then passes it to the next station. When a unit reaches the end of the line, it has passed all the stations and has become a finished product. Each station consists of the machines, workers, tools, and parts required to do its assigned task. In some cases, industrial robots do simple assembly-line tasks (see Robot). Many factories also use a conveyor belt to carry a unit from station to station (see Conveyor belt).