First-in-first-out is also known as FIFO. In this method of inventory management and valuation, the first-produced or first-bought goods are the ones that are sold, used, or disposed of first. To put it another way, merchandise is sold in the order it was received, and subsequent shipments of the same item are placed at the end of the line.
Last-in, first-out is referred to as LIFO. This approach to inventory management and valuation records the sales of the most recently produced or acquired goods first. In other words, recently received goods are accounted for before previously stored stock of the same item.