This is part of 'Data structure and algorithm implementation in python' series of blog. Previous: Stack Next: Linked List Queue: ( source code ) Direct... First in first out discipline. Let's see in real life example: The man who is standing in front of a queue is served first. That man is in front of the queue because he entered that queue at first. Formally defining: A queue is an ordered collection of items from which items are deleted from the front of the queue and the insertion of item takes place from rear of the queue. the first one inserted will be the first element to be removed. Operations done in Queue: enqueue(item): This operation inserts an item at the rare of the queue i.e. if we are using python's list to implement queue then rare means last element in the stack and every insertions after an item inserted will be appended at last of the queue. dequeue(): This operation deletes item from the front end of the queue. If we are using python's list