Migrating from a monolith to microservices breaks database transactions. When an order requires payment, inventory, and notification services, developers face distributed transaction hell. Traditional ACID transactions and BEGIN TRANSACTION won't work across separate databases. The Saga Pattern solves this by breaking a large transaction into a sequence of local transactions, each in its own service.

Instead of a global rollback, Sagas use compensating transactions to undo previous steps if a failure occurs. Think of booking a trip: if the car rental fails, you cancel the hotel and flight reservations. Two main implementation styles exist: orchestration, where a central coordinator manages the flow, and choreography, where services react to events from each other. Orchestration offers easier debugging but creates a single point of failure.

In practice, you'd build an orchestrator that logs each step and executes compensations in reverse order upon failure. Production configurations require durable queues, persistent messages, and dead letter exchanges for reliability. Key pitfalls include lack of isolation, where users see intermediate states, and the risk of compensation failures. Tools like Axon Framework, Eventuate, and Temporal can abstract away the complexity.