# Stacks and Queues

## Fundemental data types

* Value: collection of objects.
* Operations: insert, remove, iterate, test if empty.
* Intent is clear when we insert.
* Which item do we remove?
  * **Stack** : Last In First Out - **LIFO**
  * **Queue**: First in First Out - **FIFO**

![STACK, QUEUE  - INSERT , REMOVE OPERATIONS](/files/90e2XVWx1SeePbRMcMfh)

## Bag

Adding items to a collection and iterating **( Order does not matter )**

> Implementation is similar to stack / queue without pop / dequeue respectively


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