This document provides information about stacks as a data structure. Stacks are linear data structures where items can only be added or removed from one end, called the top. The last item added is the first item removed. Basic stack operations include push to insert an element and pop to remove an element. Stacks can be represented using arrays, with a variable pointing to the top element and another storing the maximum size. Functions like isEmpty() and isFull() check the state of the stack, while push() and pop() insert and remove elements.