Distributed Message Queue

A distributed message queue is a core building block that enables asynchronous communication between services. In system design interviews, message queues appear frequently—whether you're designing a notification system, an order processing pipeline, or a real-time data platform. Understanding how they work, when to use them, and how to scale them is essential for any system design discussion.

This page covers what you need for interviews: how message queues decouple services, the common messaging patterns, delivery guarantees, and how to design a distributed queue that scales horizontally while maintaining reliability.