Navigating large APIs can be challenging, but OpenAPI's tagging functionality simplifies this by allowing users to attach labels to endpoints in an OpenAPI description, enhancing navigation and documentation. Tags can group endpoints, making sections of API reference documentation more accessible, and can also include or exclude endpoint subsets from an OpenAPI description. The process involves declaring tags at the top level and adding them to relevant endpoints, as illustrated by a Museum API example with tags like "Operations," "Events," and "Tickets." Extensions such as x-displayName and x-tagGroups further enhance the user experience by offering more human-readable labels and enabling more complex categorization for large APIs. These features are supported by tools like Redocly, which can improve the clarity and usability of API documentation, and are also useful for code generation tools that may group functionalities into modules, allowing for reduced API descriptions filtered by tags.