7. The computer-implemented method of claim 1 , wherein the content described by the application page data further includes application page link data describing at least one link within the application page that links to another application page.
1. A computer-implemented method performed by data processing apparatus comprising one or more computers in data communication, the method comprising: for each application page of a native application that generates application pages for display on a user device within the native application, the native application operating independent of a browser application that can operate on the user device: extracting content from the application page, the content including content of a plurality of different content types, the content for each content type being extracted by a corresponding extractor specific to that content type; generating application page data describing content of the application page, the content described by the application page data including text that a user device displays on the application page when the user device displays the application page; and indexing the application page data for the native application in an index that is searchable by a search engine.