Introduction

• an abstract data type that represents an ordered collection of items where the addition of new items and removal of existing items takes place at the same end
• we can think of it like a stack data type just like a stack of books - if we had a stack of fifty books, we’d have to add the fifty-first book to the top of our stack, right? we probably wouldn’t be trying to stick it at the bottom of the pile of books
• the ordering principle is LIFO, or last-in first-out
  • ordering based on the length of time in a collection
  • newer items are near the top, older items are near the base
  • order of insertion is the reverse of the order of removal

Elements

Top

• the end
• the most recently added item is the one that is in the position to be removed first

Base

• the opposite of the top
• items stored closer to the base are those that have been in the stack the longest

Push

• insert a new element on the top of the stack

Pop

• remove and return the most recently added element, the element at the top of the stack

Usages