The opposite of "F.I.F.O." (First In First Out). With LIFO earlier orders are delayed in favor of newer orders which results in increased lead-time and unhappy customers regarding the earlier orders. and etc. Many advanced material handling systems, stacking systems, and simple KanBan methods can keep your inventory stocked in FIFO order to avoid the many pitfalls of LIFO failings. All that said, there are times when LIFO measures seem essential. If a customer who represents the majority of your sales requests something immediately it is very difficult to tell them they must wait their turn.