The document discusses using the LinkedIn API for building applications. It provides an overview of the JavaScript and REST APIs, noting that the JavaScript API is easier to use but more limited while the REST API provides more flexibility but requires more development effort. Both APIs require user authorization. The document then describes some of the capabilities of the LinkedIn API, such as accessing profile and connection data, performing faceted people searches, and accessing jobs and group data. It also outlines some rules for using the API related to data storage and exposure.