FIFO (computing and electronics)

In computing and in <a href="/facts/Systems_theory/C56Ck7DQ">systems theory</a>, first in, first out (the first in is the first out), <a href="/facts/Acronym/nlHK7aRt">acronymized</a> as FIFO, is a method for organizing the manipulation of a data structure (often, specifically a <a href="/facts/Data_buffer/tVy4j2Dc">data buffer</a>) where the oldest (first) entry, or "head" of the <a href="/facts/Queue_(data_structure)/hVPjPXus">queue</a>, is processed first.
Such processing is analogous to servicing people in a <a href="/facts/Queue_area/eMfW0LCb">queue area</a> on a <a href="/facts/First-come%2c_first-served/8NDl56EM">first-come, first-served</a> (FCFS) basis, i.e. in the same sequence in which they arrive at the queue's tail.
FCFS is also the <a href="/facts/Jargon/eI6scBdF">jargon</a> term for the FIFO <a href="/facts/Scheduling_(computing)/XptmcM1a">operating system scheduling</a> algorithm, which gives every process <a href="/facts/Central_processing_unit/Jxp1bqMV">central processing unit</a> (CPU) time in the order in which it is demanded. FIFO's opposite is <a href="/facts/LIFO_(computing)/bj7l94v1">LIFO</a>, last-in-first-out, where the youngest entry or "top of the stack" is processed first. A <a href="/facts/Priority_queue/1uXVo4Uf">priority queue</a> is neither FIFO or LIFO but may adopt similar behaviour temporarily or by default. <a href="/facts/Queueing_theory/8NDl56EM">Queueing theory</a> encompasses these methods for processing <a href="/facts/Data_structures/yNsNvL1I">data structures</a>, as well as interactions between strict-FIFO queues.

FIFO (computing and electronics) open-in-new

FIFO (computing and electronics)