Today’s web is built predominantly for human consumption. Even as machine-readable data begins to appear on the web, it is typically distributed in a separate file, with a separate format, and no correspondence between the human and machine versions. As a result, web browsers can provide only minimal assistance to humans in parsing and processing web data: browsers only see presentation information. We introduce RDFa, which provides a set of HTML attributes to augment visual data with machine-readable hints. We show how to express simple and more complex datasets using RDFa, and in particular how to turn the existing human-visible text and links into machine-readable data without repeating content.