The Distributed Annotation System (DAS) defines a communication protocol used to exchange biological sequence annotations. DAS is a client-server system in which a single client integrates data from multiple servers.
Data distribution, performed by DAS servers, is separated from visualization, which is done by DAS clients. Little coordination is needed among the various information providers.
DAS is heavily used in the genome bioinformatics community for sharing information about gene and protein sequences as well as protein structures.