Databases

BioSystems
Database that groups biomedical literature, small molecules, and sequence data in terms of biological relationships.
Database of Expressed Sequence Tags (dbEST)
A divison of GenBank that contains short single-pass reads of cDNA (transcript) sequences. dbEST can be searched directly through the Nucleotide EST Database.
Database of Genome Survey Sequences (dbGSS)
A division of GenBank that contains short single-pass reads of genomic DNA. dbGSS can be searched directly through the Nucleotide GSS Database.
GenBank
The NIH genetic sequence database, an annotated collection of all publicly available DNA sequences. GenBank is part of the International Nucleotide Sequence Database Collaboration, which comprises the DNA DataBank of Japan (DDBJ), the European Molecular Biology Laboratory (EMBL), and GenBank at NCBI. These three organizations exchange data on a daily basis. GenBank consists of several divisions, most of which can be accessed through the Nucleotide database. The exceptions are the EST and GSS divisions, which are accessed through the Nucleotide EST and Nucleotide GSS databases, respectively.
NCBI Website Search
A database of static NCBI web pages, documentation, and online tools. These pages include such content as specialized online sequence analysis tools, back issues of newsletters, legacy resource description pages, sample code, and other miscellaneous resources.
Nucleotide Database
A collection of nucleotide sequences from several sources, including GenBank, RefSeq, the Third Party Annotation (TPA) database, and PDB. Searching the Nucleotide Database will yield available results from each of its component databases.
PopSet
A database of DNA sequences that have been collected to analyze the evolutionary relatedness of a population. The population could originate from different members of the same species, or from organisms from different species.
Probe
A public registry of nucleic acid reagents designed for use in a wide variety of biomedical research applications, together with information on reagent distributors, probe effectiveness, and computed sequence similarities.
Reference Sequence (RefSeq)
A collection of curated, non-redundant genomic DNA, transcript (RNA), and protein sequences produced by NCBI. RefSeqs provide a stable reference for genome annotation, gene identification and characterization, mutation and polymorphism analysis, expression studies, and comparative analyses. The RefSeq collection is accessed through the Nucleotide and Protein databases.
Sequence Read Archive (SRA)
The Sequence Read Archive (SRA) stores sequencing data from the next generation of sequencing platforms including Roche 454 GS System®, Illumina Genome Analyzer®, Life Technologies AB SOLiD System® , Helicos Biosciences Heliscope®, Complete Genomics®, and Pacific Biosciences SMRT®
Third Party Annotation (TPA) Database
A database that contains sequences built from the existing primary sequence data in GenBank. The sequences and corresponding annotations are experimentally supported and have been published in a peer-reviewed scientific journal. TPA records are retrieved through the Nucleotide Database.
Trace Archive
A repository of DNA sequence chromatograms (traces), base calls, and quality estimates for single-pass reads from various large-scale sequencing projects.

Tools

BLAST (Basic Local Alignment Search Tool)
Finds regions of local similarity between biological sequences. The program compares nucleotide or protein sequences to sequence databases and calculates the statistical significance of matches. BLAST can be used to infer functional and evolutionary relationships between sequences as well as to help identify members of gene families.
E-Utilities
Tools that provide access to data within NCBI's Entrez system outside of the regular web query interface. They provide a method of automating Entrez tasks within software applications. Each utility performs a specialized retrieval task, and can be used simply by writing a specially formatted URL.
Genome Workbench
An integrated application for viewing and analyzing sequence data. With Genome Workbench, you can view data in publically available sequence databases at NCBI, and mix these data with your own data.
Influenza Virus
Presents data from the NIAID Influenza Genome Sequencing Project and from GenBank, and provides tools for flu sequence analysis, annotation and submission to GenBank. It also provides links to other flu sequence resources, and publications and general information about flu viruses.
VecScreen
A system for quickly identifying segments of a nucleic acid sequence that may be of vector origin. VecScreen searches a query sequence for segments that match any sequence in a specialized non-redundant vector database (UniVec).

Downloads

Batch Nucleotide
Allows you to retrieve a large number of sequences from Entrez in a batch mode by importing a file containing a list of the desired GI or accession numbers. Search results are saved directly to a local disk file on your computer.
FTP: GenBank
This site contains files for all sequence records in GenBank in the default flat file format. The files are organized by GenBank division, and the full contents are described in the README.genbank file.
FTP: RefSeq
This site contains all nucleotide and protein sequence records in the Reference Sequence (RefSeq) collection. The "release" directory contains the most current release of the complete collection, while data for selected organisms (such as human, mouse and rat) are available in separate directories. Data are available in FASTA and flat file formats. See the README file for details.
FTP: UniVec
This site contains the UniVec and UniVec_Core databases in FASTA format. See the README.uv file for details.

Submissions

BankIt
A web-based sequence submission tool for one or a few submissions, designed to make the submission process quick and easy.
Barcode Submission
Tool to submit Barcodes, short nucleotide sequences from a standard genetic locus for use in species identification.