OpenAPI and Swagger are API description formats that provide a standardized, machine-readable framework for documenting HTTP APIs, offering a solution to the common issue of outdated or incomplete API documentation. By utilizing OpenAPI or Swagger, developers benefit from automated, up-to-date documentation that accurately reflects the architecture of an API, improving the developer experience by ensuring clarity and consistency. These formats, which can be written in YAML or JSON, enable comprehensive and consistent API documentation, automated testing for API validity, and the generation of additional tools such as servers, SDKs, and sample code. OpenAPI evolved from Swagger to become a vendor-neutral standard supported by the OpenAPI Initiative, which includes major tech companies and is governed by the Linux Foundation. The current major version is OpenAPI 3.0, which introduced improvements such as a "components" section for greater flexibility. The integration of OpenAPI or Swagger files into continuous integration and delivery pipelines ensures that documentation remains synchronized with API deployments, ultimately enhancing the overall API lifecycle.