Activities Operating on Structured Data

Various embodiments can enable a webpage publisher to describe structured data on a webpage in a manner that enables a Web browser to intelligently present activities that pertain to user selections relative to the structured data appearing on the webpage. In at least some embodiments, a webpage publisher can provide markup that identifies structured data on a webpage. A service provider can provide a representation that describes the types of structured data in which it is interested, and how to handle the structured data responsive to a user selection. The Web browser can then use the markup in the webpage and the service provider's representation to identify and present activities associated with structured data selected by the user.