STRING is a comprehensive database that predicts functional associations between proteins based on genomic context. The database integrates three types of evidence—recurring neighborhood, phylogenetic co-occurrence, and gene fusion events—to assess and compare the significance of individual predictions. It uses a unique scoring framework that combines these types of evidence into a single confidence score for each prediction. STRING provides a high-level view of functional linkage through a graphical representation of the network of inferred, weighted protein interactions, facilitating the analysis of modularity in biological processes. The database is continuously updated and currently includes 261,033 orthologs from 89 fully sequenced genomes, with predictions achieving an expected accuracy of at least 80% for more than half of the genes. Users can access STRING online at http://www.bork.embl-heidelberg.de/STRING/ to explore functional links for specific proteins.STRING is a comprehensive database that predicts functional associations between proteins based on genomic context. The database integrates three types of evidence—recurring neighborhood, phylogenetic co-occurrence, and gene fusion events—to assess and compare the significance of individual predictions. It uses a unique scoring framework that combines these types of evidence into a single confidence score for each prediction. STRING provides a high-level view of functional linkage through a graphical representation of the network of inferred, weighted protein interactions, facilitating the analysis of modularity in biological processes. The database is continuously updated and currently includes 261,033 orthologs from 89 fully sequenced genomes, with predictions achieving an expected accuracy of at least 80% for more than half of the genes. Users can access STRING online at http://www.bork.embl-heidelberg.de/STRING/ to explore functional links for specific proteins.