Page "FIFO" Paragraph 1

FCFS is also the jargon term for the FIFO operating system scheduling algorithm, which gives every process CPU time in the order they come.

In the broader sense, the abstraction LIFO, or Last-In-First-Out is the opposite of the abstraction FIFO organization.

The difference perhaps is clearest with considering the less commonly used synonym of LIFO, FILO ( meaning First-In-Last-Out ).

In essence, both are specific cases of a more generalized list ( which could be accessed anywhere ).

The difference is not in the list ( data ), but in the rules for accessing the content.

One sub-type adds to one end, and takes off from the other, its opposite takes and puts things only on one end.