This document discusses various message queue technologies including RabbitMQ, ZeroMQ, cloud-based options like Azure Service Bus and Amazon SQS/SNS, and the lightweight NATS system. It provides overviews of each technology, highlighting key features, protocols, and use cases. Examples and code demos are shown for RabbitMQ and ZeroMQ. The document aims to help readers understand different message queue options and pick the most suitable one based on their distributed system and cloud hosting needs.