Definition
A message queue is a communication construct that enables different parts of a software application, or entirely separate applications, to exchange information asynchronously. It acts as an intermediary buffer, holding messages until the receiving application is ready to process them, decoupling senders from receivers. This allows systems to operate independently, improving resilience and scalability by preventing failures in one component from immediately impacting others. For instance, an e-commerce order processing system might use a message queue to handle incoming orders, ensuring no order is lost even if the inventory or shipping services are temporarily unavailable. Unlike a direct API call which requires immediate response, a message queue facilitates eventual consistency. Message queues are fundamental concepts tested on certifications like AWS Certified Solutions Architect Associate and CCSP.