An event-driven architecture (EDA) is an architecture pattern designed to connect service components and enable complex systems to communicate. Event-driven architectures are comprised of three key components:

1. Event producers (e.g., software as a service (SaaS) app, mobile app, ecommerce site, point-of-sale)

2. Event brokers (e.g., event router, event store)

3. Event consumers (e.g., database, microservice, SaaS application)

Events indicate a change in state (order placed, user created) and are passed between components as messages with specific semantics. A producer publishes an event to the broker, which abstracts producers and consumers from one another by allowing them to communicate asynchronously. EDAs use events to coordinate communication between loosely coupled services.