FIFO stands for First-In-First-Out. It is a method of organizing data in a queue, where the first item added to the queue is the first one to be removed. This contrasts with a LIFO (Last-In-First-Out) queue, where the last item added to the queue is the first one to be removed.

FIFO is commonly used in computer science and programming, especially in the implementation of queues, which are a type of data structure used to store and manage data. In a queue, new elements are added to the end of the queue, and the first element in the queue is removed first, following the FIFO principle.

FIFO is used in a variety of applications, including CPU scheduling, data transmission, and simulations, where the order of elements needs to be maintained. It ensures that the oldest data is processed first, making it a useful method for managing and organizing data in a time-sensitive manner.