When browsing the Web, you would often like to know what people think about the site you are visiting; sanno in Italian means "they know", and the main goal of this project is to let people share semantic annotations about any resource reachable on the Web. Filtering and browsing annotations coming from distributed and heterogeneous sources is made possible by a general and flexible model based on named graphs; while the vocabulary about annotation metadata is well defined and fixed, any RDF property can be used to describe a Web resource, though the convergence on shared vocabularies is boosted.

The framework is designed to be distributed, based on the fact that information is provided in a specific semantic format and users can subscribe only to the annotation sources they like and/or trust.

The system relies on user participation but can be bootstrapped thanks to the conversion of already existing structured or semi-structured annotation systems. Semantic annotations can finally be shown through a browser extension, which relies on predefined visualization techniques to manage different families of properties.