What is the onion architecture?

Part 2 of the functional architecture series. When we’re structuring our functional software, we want to isolate the actions from the calculations. We can do that using the Onion Architecture, which has layers like an onion. The center of the onion is your domain model, then around that are your business rules. Finally, around that is your interaction layer, which talks with the outside world, including the database, web requests, api endpoints, and the UI.