OpenAPI
OpenAPI is a specification for describing RESTful APIs in a machine-readable format, originally known as Swagger. It allows developers to define API endpoints, request/response structures, authentication methods, and other details using YAML or JSON. This enables automatic generation of documentation, client SDKs, and server stubs, improving API consistency and developer experience.
Developers should learn OpenAPI when building, documenting, or consuming REST APIs, as it standardizes API design and facilitates collaboration between frontend and backend teams. It is particularly useful in microservices architectures, API-first development, and automated testing, where clear API contracts reduce integration errors and speed up development cycles.