Introduction
The state of some structures reflects their history.
Two main operations are : add and remove items
Example: a line at a ticket booth, stack of dishes to be washed.
Linear structures are structures that grow and shrink in a predetermined order.
Last In First Out (LIFO) and First In First Out (FIFO) are two such orders.
Stacks operate on LIFO basis, and Queues in an FIFO order.