Representation of Stack
  1. A stack can be represented by means of Array, Structure, Pointer, and Linked List.
  2. Stack can either be a fixed size one or it can be of dynamic resizing that means the size of the stack can be changed dynamically. 
  3. Applications:

    1. The simplest application of a stack is to reverse a word. You push a given word to stack - letter by letter - and then pop letters from the stack.

    2. Another real life application is  a book set where a upper book can we taken easily.