An architecture where services communicate by emitting and reacting to events instead of calling each other directly.
Event-driven architecture (EDA) is a pattern where services emit events ('order.placed', 'user.signed-up') to a broker (Kafka, EventBridge, NATS, Pub/Sub) and other services subscribe to the events they care about. The producer doesn't know who's consuming; the consumer doesn't know who's producing. The pattern decouples services, smooths load via the broker's queue, and creates a natural audit log of everything that happened in the system.
Synchronous request/response architectures couple services tightly, a downstream's slowness is an upstream's outage. EDA breaks that coupling: the upstream emits and moves on, the downstream consumes when ready. The tradeoff is consistency, eventually-consistent state and harder transactional reasoning, in exchange for resilience and scalability.
See the part of the platform that handles event-driven architecture in production.