Like many other databases that store protein association knowledge, STRING imports data from experimentally derived protein–protein interactions through literature curation.  Furthermore, STRING also store computationally predicted interactions from: (i) text mining of scientific texts, (ii) interactions computed from genomic features, and 
(iii) interactions transferred from model organisms based on orthology.
All predicted or imported interactions are benchmarked against a common reference of functional partnership as annotated by KEGG (Kyoto Encyclopedia of Genes and Genomes).