This document discusses stacks and queues as linear data structures. Stacks follow the LIFO (Last In First Out) principle, while queues follow the FIFO (First In First Out) principle. Both can be implemented using arrays or linked lists. Common operations on stacks include push, pop, and display. Common operations on queues include enqueue, dequeue, front, and size. The document provides examples of applications for each including number reversing, undo operations, and depth-first search for stacks and message queues for queues.