The Outbox Pattern is a design pattern in distributed systems that is used to ensure reliable event publishing and state consistency between different services or databases. It is primarily used in scenarios like when a system is required to update a database and publish events atomically.

In distributed systems, there are often challenges in maintaining consistency during the process of writing to a database and sending messages. For example, consider a payment processing system where you are required to update the transaction status in the database and send an event to another service about the status that got updated (e.g., payment confirmation event). If either the database update fails or the message fails publishing fails, inconsistencies can arise in the current system or another system that failed to consume the event, potentially leading to business losses.