In computer science, a queue is an abstract data type that serves as an ordered collection of entities. By convention, the end of the queue where elements are added, is called the back, tail, or rear of the queue. The end of the queue where elements are removed is called the head or front of the queue. The name queue is an analogy to the words used to describe people in line to wait for goods or services. It supports two main operations.Enqueue, which adds one element to the rear of the queue Dequeue, which removes one element from the front of the queue.