Also see named pipe (somtimes referred to as a "fifo").
In computer programming, FIFO (first-in, first-out) is an approach to handling program work requests from queues or stacks so that the oldest request is handled next. LIFO (last-in, first-out) is an approach in which the most recent request is handled next and the oldest request doesn't get handled until it is the only remaining request on the queue (or in the stack). Although LIFO seems "unfair," it may be more efficient. A stack that is handled using LIFO is sometimes referred to as a push-down or push-down pop-up stack or list.