A Closed-Won opportunity is an opportunity that has been won by a sales rep and is no longer open. This means that the deal has been officially closed and the customer is satisfied with the product or service purchased. The process of moving an opportunity from open to closed-won can vary depending on the organization, but typically includes some kind of final review or sign-off from the customer. Once an opportunity is closed-won in Salesforce, it's considered part of the win/loss analysis for your business. This data can be used to help improve future sales strategies.