Java Message Service (JMS) is a messaging standard that allows different applications to communicate with each other in a reliable and asynchronous manner. It enables the exchange of messages between software components, which can be running on different servers or platforms, without needing to know the details of each other's implementation. JMS supports two messaging models: point-to-point and publish-subscribe. In the point-to-point model, messages are sent from one producer to one consumer, ensuring that each message is processed only once. In the publish-subscribe model, messages are sent from producers to multiple subscribers, allowing for broader distribution of information.