The publish/subscribe (pub/sub) pattern is a design architecture that allows for asynchronous sending and receiving of messages by a broker dedicated to the task, providing applications with increased scalability compared to other message exchange patterns. This loose coupling makes it a powerful solution for many common engineering challenges such as event notification, distributed caching, distributed logging, multiple data sources, and burstability and scale. Pub/sub messaging is used in various industries and can be implemented using platforms like Ably.