FIFO

This term is a technical acronym used primarily in computer science and accounting. In computing, it describes a specific data structure (a queue) where the sequence of processing is strictly chronological. In accounting, it refers to a cost-flow assumption used to calculate the value of inventory and the cost of goods sold.

Because it is an acronym, it is frequently written in all capital letters. While it functions as a noun, it is often used attributively as a modifier for other nouns, such as in "FIFO buffer" or "FIFO method."