This unit describes the NCBI's Entrez database browser. Entrez integrates DNA and protein sequence data, three dimensional structures, and taxonomic information with its associated abstracts and citations contained in PubMed (MEDLINE). It is possible to search the Entrez information space using conventional search queries (authors, gene names, map location) as well as by bibliographic associations (articles that are related to one another) and sequence homology. Also described are the procedures for submission of new data, updates, and corrections to the sequence databases.