Queues

This lesson covers queues — a fundamental abstract data type (ADT) following the FIFO principle. Queues appear extensively in the OCR A-Level Computer Science (H446) specification and have many practical applications in computing.

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What is a Queue?

A queue is a linear data structure that follows the FIFO (First In, First Out) principle. The first item added is the first item to be removed — like a queue of people waiting in line.

Real-World Analogies

• A queue at a supermarket checkout: first person in line is served first.
• Print jobs: the first document sent to the printer is printed first.
• Customer service calls: callers are answered in the order they called.

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Queue Operations