Standard Article

Entrez and Forward Database Searching

  1. Fran Lewitter

Published Online: 15 DEC 2009

DOI: 10.1002/9780470015902.a0003035.pub2



How to Cite

Lewitter, F. 2009. Entrez and Forward Database Searching. eLS. .

Author Information

  1. Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, USA

Publication History

  1. Published Online: 15 DEC 2009


Entrez is a text-based search system that provides integrated access to multiple databases of interest to the molecular biology community. It was developed by and is available through a website ( at the National Center for Biotechnology Information (NCBI). This tool provides the ability to query one or multiple databases. The interface also allows both simple and advanced searching. For example, one can enter one or a few terms in a search box to initiate a simple search, or, one can limit search terms to particular fields or use a controlled vocabulary. In addition, results include links to related entries and other relevant information that match the search criteria. The output can be saved to a local computer for further processing. There are also advanced tools – web-based or programming tools – some discussed later.

Key concepts:

  • Entrez provides access to many different biologically oriented databases.

  • To restrict your search use features of Limits or Preview/Index.

  • Use ‘Batch Entrez’ to download lists of identifiers.

  • There are specific search options available for each database.

  • Help text specific to each database is available on its homepage.

  • Register for a My NCBI account so that you can define and store preferences and save search results.

  • There are several ways to download data retrieved from an Entrez search to a local computer.

  • The History feature is helpful to combine previous searches.


  • text searching;
  • literature searching;
  • molecular databases