Table 1. The Entrez databases (as of 3 September 2014).

Database	Records	Section within this article	Data sourcea
Site search	21 929	Introduction	N
MedGenb	260 796	Recent developments	C, N
ClinVarb	124 671	Recent developments	D, N
GTRb	32 152	Recent developments	D
PubMed	24 157 837	Literature	C
PubMed Central	3 201 919	Literature	D, C
NLM Catalog	1 507 828	Literature	C, N
MeSH	253 057	Literature	N
Books	337 275	Literature	C, N
Taxonomyb	1 288 515	Taxonomy	C, N
Nucleotideb	146 035 069	DNA and RNA	D (GenBank), C, N
ESTb	75 673 561	DNA and RNA	D (GenBank)
GSSb	37 613 795	DNA and RNA	D (GenBank)
BioSample	2 734 070	DNA and RNA	D
SRAb	963 108	DNA and RNA	D
PopSetb	207 794	DNA and RNA	D (GenBank)
Proteinb	147 483 171	Proteins	C, N
Protein Clustersb	820 546	Proteins	N
Structureb	102 343	Proteins	C, N
CDDb	49 641	Proteins	C, N
GEO Profilesb	108 686 654	Genes and expression	D
Probe	31 887 935	Genes and expression	D
Geneb	17 530 632	Genes and expression	C, N
UniGeneb	6 473 284	Genes and expression	N
GEO Data Setsb	1 295 573	Genes and expression	D
Biosystemsb	619 468	Genes and expression	C
Homologeneb	141 268	Genes and expression	N
Cloneb	36 916 420	Genomes	D, N
BioProjectb	134 582	Genomes	D
Assembly	32 501	Genomes	C, N
Genomeb	10 244	Genomes	C, N
Epigenomicsb	6634	Genomes	D
SNPb	394 164 715	Genetics and medicine	D (dbSNP), N
dbVarb	4 155 758	Genetics and medicine	D
dbGaP	163 310	Genetics and medicine	D
PubMed Health	49 278	Genetics and medicine	C
PubChem Substanceb	157 203 085	Chemicals and bioassays	D
PubChem Compoundb	53 371 491	Chemicals and bioassays	N
PubChem Bioassayb	1 091 044	Chemicals and bioassays	D

^aD = direct submission; C = collaboration/agreement; N = internal NCBI/NLM curation.

^bIndicates that the data in this resource are available by FTP.