An acronym for First In, First Out. This expression describes the principle of a queue: what comes in first is handled first, what comes in next waits until the first is finished, etc. It is analogous to the behavior of persons “standing in a line” where the persons leave the line in the order they arrive.
The expression FIFO can be used in different contexts:
In computers this term refers to the way data stored in a queue is processed. Each item in the queue is stored in a queue data structure. The first data to be added to the queue will be the first data to be removed, then processing proceeds sequentially in the same order. This is typical behavior for the information that is sent to a CPU.
You have encountered FIFO structure if you have ever set or altered your audio software’s buffer settings. The buffer is a software-defined queue; whether it’s defined in samples or milliseconds, you’re increasing or decreasing the size of the queue.
In electronics a FIFO is a semiconductor memory in which the first data to be written is always the first data to be read. A common application of this is computer or sampler RAM. The function includes address counters and control logic. A FIFO with a clock input is called “synchronous” as in SDRAM; otherwise it is asynchronous.