First in - First out means that the first product that enters the machine is also the first one to leave again. This usually means that the product sequence stays intact which can be a critical feature for various types of productions. An example could be batch tracing within liquid filling or pharmacy. Alternatively, First in - Last out means that the first product that enters the line is that last one to leave when the products are fed out of the system. These types of systems can be cheaper, and could be used in system where a set sequence isnt relevant. An example could be non-perischable products or those that don't have time sensitive processes.