Queues

This lesson covers the queue — a fundamental Abstract Data Type that follows the First-In, First-Out (FIFO) principle. Queues are used in many computing applications, from printer spooling to process scheduling. This lesson covers linear, circular, and priority queues.

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What is a Queue?

A queue is an ordered collection of elements where:

• Items are added (enqueued) at the rear (back) of the queue.
• Items are removed (dequeued) from the front of the queue.
• The first item added is the first to be removed — FIFO.

Think of a queue at a shop: the first person to join is the first to be served.

FRONT → [ 10 | 20 | 30 | 40 ] ← REAR
         ↑ dequeue here          ↑ enqueue here

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Queue Operations