"message queues and mailboxes are software-engineering components used for inter-process communication (IPC), or for inter-thread communication within the same process. They use a queue for messaging – the passing of control or of content." - Wikipedia
Message queue is a software components that allow producers to produce message to a queue managed by a message broker, these message are asynchronously consumed by consumers.
Message Queue Basics
Protocols : Advanced Message Queueing Protocol(AMQP) and Streaming Text Oriented Messaging Protocol(STOMP)
Types of Queue: Direct, Topic and Fanout
Message Broker - Queue Exchange
Benefits of MQ
Fanout - Same message to multiple queues (Pub/Sub)