A message queue is a form of asynchronous service-to-service communication used in serverless and microservices architectures. It enables different components of a system to communicate and process operations without needing to interact in real-time. Messages, which are discrete units of data, are placed into a queue by producers and retrieved by consumers. This decoupling of producers and consumers enhances system resilience and scalability, allowing applications to handle varying loads gracefully.

Message queues are particularly useful for load balancing, task scheduling, and reliable message delivery. They ensure that messages are processed sequentially and can be stored until the consumer is ready, which helps prevent system overload and data loss. Technologies like RabbitMQ, Amazon SQS, and Apache Kafka implement message queuing, supporting various use cases from simple task queues to complex event-driven architectures. This approach not only improves the robustness of applications but also simplifies the integration and orchestration of disparate system components.