Connotea [1] is a free online reference management and social bookmarking service for scientists created by Nature Publishing Group [2]. While somewhat experimental in nature, Connotea already has a large and growing number of users, and is a real, fully functioning service [3]. The label 'experimental' is not meant to imply that the service is any way ephemeral or esoteric, rather that the concept of social bookmarking itself and the application of that concept to reference management are both recent developments. Connotea is under active development, and we are still in the process of discovering how people will use it. In addition to Connotea being a free and public service, the core code is freely available under an open source license [4].

Connotea, the Nature Publishing Group's answer to del.icio.us <http://del.icio.us>, is an online social bookmarking tool designed for scientists.