What is Onion Architecture?

Onion Architecture is a software architecture pattern that emphasizes separation of concerns and promotes maintainability and testability. It structures an application into concentric layers, with the core business logic at the center and external concerns like UI and infrastructure at the outer layers. Dependencies point inward, meaning the core is independent of the outer layers, allowing changes in the outer layers without affecting the core. It is commonly used to create loosely coupled, adaptable applications.