Darwin Core (often abbreviated to DwC) is a body of data standards which function as an extension of Dublin Core for biodiversity informatics applications, establishing a vocabulary of terms to facilitate the discovery, retrieval, and integration of information about organisms, their spatiotemporal occurrence, and supporting evidence housed in biological collections. It is meant to provide a stable standard reference for sharing information on biological diversity.
By providing a well-defined standard core vocabulary, Darwin Core aims to facilitate data sharing in biodiversity research by minimizing the barriers to adoption and maximizing reusability. The terms described in this standard are a part of a larger set of vocabularies and technical specifications under development and maintained by Biodiversity Information Standards (formerly known as the Taxonomic Databases Working Group (TDWG)).
The Darwin Core is a body of standards. It includes a glossary of terms (in other contexts these might be called properties, elements, fields, columns, attributes, or concepts) intended to facilitate the sharing of information about biological diversity by providing reference definitions, examples, and commentaries. The Darwin Core is primarily based on taxa, their occurrence in nature as documented by observations, specimens, and samples, and related information. Included in the standard are documents describing how these terms are managed, how the set of terms can be extended for new purposes, and how the terms can be used. The Simple Darwin Core  is a specification for one particular way to use the terms - to share data about taxa and their occurrences in a simply structured way - and is probably what is meant if someone suggests to "format your data according to the Darwin Core".
Each term has a definition and commentaries that are meant to promote the consistent use of the terms across applications and disciplines. Evolving commentaries that discuss, refine, expand, or translate the definitions and examples are referred to through links in the Comments attribute of each term. This approach to documentation allows the standard to adapt to new purposes without disrupting existing applications. There is meant to be a clear separation between the terms defined in the standard and the applications that make use of them. For example, though the data types and constraints are not provided in the term definitions, recommendations are made about how to restrict the values where appropriate.
In practice, Darwin Core decouples the definition and semantics of individual terms from application of these terms in different technologies such as XML, RDF or simple CSV text files. Darwin Core provides separate guidelines on how to encode the terms as XML or text files.
Darwin Core was originally created as a Z39.50 profile by the Z39.50 Biology Implementers Group (ZBIG), supported by funding from a USA National Science Foundation award. The name "Darwin Core" was first coined by Allen Allison at the first meeting of the ZBIG held at the University of Kansas in 1998 while commenting on the profile's conceptual similarity with Dublin Core. The Darwin Core profile was later expressed as an XML Schema document for use by the Distributed Generic Information Retrieval (DiGIR) protocol. A TDWG task group was created to revise the Darwin Core, and a ratified metadata standard was officially released on 9 October 2009.
Though ratified as a TDWG/Biodiversity Information Standards standard since then, Darwin Core has had numerous previous versions in production usage. The published standard contains a history with details of the versions leading to the current standard.
|Name||Namespace||Number of terms||XML Schema||Date Issued|
|Darwin Core 1.0||Not Applicable||24||(Z39.50 GRS-1)||1998|
|Darwin Core 1.2 (Classic)||http://digir.net/schema/conceptual/darwin/2003/1.0||46||||2001-09-11|
|Darwin Core 1.21 (MaNIS/HerpNet/ORNIS/FishNet2)||http://digir.net/schema/conceptual/darwin/2003/1.0||63||||2003-03-15|
|Darwin Core OBIS||http://www.iobis.org/obis||27||||2005-07-10|
|Darwin Core 1.4 (Draft Standard)||http://rs.tdwg.org/dwc/dwcore/||45||||2005-07-10|
|Darwin Core Terms (properties)||http://rs.tdwg.org/dwc/terms/||172||||2009-10-09|
Key Projects Using Darwin Core
- The Global Biodiversity Information Facility (GBIF)
- The Ocean Biogeographic Information System (OBIS)
- The Atlas of Living Australia (ALA)
- Online Zoological Collections of Australian Museums (OZCAM)
- Mammal Networked Information System (MaNIS)
- Ornithological Information System (ORNIS)
- FishNet 2
- Sistema Nature 3.0
- Encyclopedia of Life
- Darwin Core Archive
- Biodiversity Information Standards (TDWG)
- Biodiversity informatics
- Metadata standards
- Wieczorek, John; D. Bloom, R. Guralnick, S. Blum, M. Döring, R. De Giovanni, T. Robertson, and D. Vieglais (2012). "Darwin Core: An Evolving Community-developed Biodiversity Data Standard.". PLoS ONE 7 (1). doi:10.1371/journal.pone.0029715. PMC 3253084. PMID 22238640.
- The Simple Darwin Core
- Darwin Core XML Guide
- Darwin Core Text Guide
- An Experimental Z39.50 Information Retrieval Protocol Test Bed for Biological Collection and Taxonomic Data, #9811443 
- Darwin Core History
- "Darwin Core". Global Biodiversity Information Facility. Retrieved April 12, 2011.
- "Data Schema and metadata". Ocean Biogeographic Information System. Retrieved April 12, 2011.