Stack

A stack is a linear Structure in which item may be added or removed only at one end. There are certain frequent situations in computer science when one wants to restrict insertions and deletions so that they can take place only at the beginning or the end of the end of the list, not in the middle. Two of the Data Structures that are useful in such situations are Stacks and queues. A stack is a list of elements in which an elements may be inserted or deleted only at one end, called the Top. This means, in particular, the elements are removed from a stack in the reverse order of that which they are inserted in to the stack. The stack also called "last-in first -out (LIFO) " list.

Special terminology is used for two basic operation associated with stack :

1. "Push" is the term used to insert an element into a stack.
2. "Pop" is the term used to delete an element from a stack.