The document discusses the Tableau API and why a developer may want to use it. The Tableau API includes the Document API, Extract API, JS API, REST API/TSC library, and Web Data Connector. It allows developers to extend Tableau's functionality, automate tasks, customize visualizations, and integrate visualizations into other applications. The APIs provide programmatic access to create and modify Tableau reports, create extracts, embed visualizations, and manage Tableau Server.