A message queuing system is a software component that enables different applications or services to communicate with each other by sending messages. It acts as a middleman, storing messages sent from one application until the receiving application is ready to process them. This ensures that messages are not lost, even if the receiving application is busy or temporarily unavailable. These systems help improve the reliability and scalability of applications. By decoupling the sender and receiver, they allow for asynchronous communication, meaning that the sender can continue its work without waiting for the receiver to respond. Popular examples of message queuing systems include RabbitMQ, Apache Kafka, and Amazon SQS.