the web’s open architecture guarantees that one way or another, it’s possible to create and share authoritative overlays. Annotation tools and services are converging on open standards that will enable them to work with one another,3 just as different kinds of web browser and email clients are able to work with different kinds of web and email servers. This movement toward open and interoperable web annotation sets the stage for a democratization of the scholarly arts of close reading, line-by-line analysis, and accurate citation.