FIFO and LIFO

FIFO First in First out

an abstraction in ways of organizing and manipulation of data relative to time and prioritization. This expression describes the principle of a queue processing technique or servicing conflicting demands.
 
Queues = First in first out
Queues have two pointers : Head pointer, Tale Pointer

Example:
Print Queue

LIFO Last in First out

This refers to the way items stored in some types of data structures are processed. By definition, in a LIFO structured linear list, elements can be added or taken off from only one end, called the "top" A LIFO structure can be illustrated with the example of a stack of trays. The last tray to be placed on top is also the first to be taken off the top