A queue is a simple data structure that allows elements to be inserted from one end, called the rear (also called tail), and deleted from the other end, called the front (also called head).
This behavior is called FIFO (First in First Out).
Terminology
The process of adding new elements into the queue is called enqueue.
The process of removal of an element from the queue is called dequeue.
Applications
Queues are used whenever we need to manage objects in order starting with the first one in.
Scenarios include printing documents on a printer, call center systems answering people on hold people, and so on.
A queue can be implemented using an array or a linked list.