API documentation provides information about how to use an application programming interface (API). It explains what an API is, how APIs allow applications to interact and exchange data, and the benefits of using APIs. The documentation also describes how APIs work by sending requests and receiving responses, and who typically creates APIs and their documentation. It provides details on API requests and responses, different types of APIs, and who the target audience of API documentation is. It recommends tools like Swagger that can automatically generate API documentation from code annotations to help technical writers complement the generated documentation.