Digital Object Identifiers: what they are and where to find them
FAQ: What is a DOI and how can find out if my work has one?
A Digital Object Identifier, or DOI, uniquely and permanently identifies an object. Although the ‘object’ in theory may be any entity (physical, digital or abstract), in practice the most frequent use of DOI names is to describe the location of electronic journal articles, data sets and other digital documents. To date over 84 million DOI names have been assigned (see DOI Factsheet), each with a set of basic metadata and a pointer to the full content.
The principle behind the DOI system is that clicking on a DOI name will take you straight to the definitive copy of the item, irrespective of whether its web address (URL) has changed.
To achieve this, participating publishers sign up with a DOI registration agency, such as CrossRef or DataCite. They then allocate a unique DOI name to each item published and send appropriate metadata, including the location of the item, to the agency. If the actual location of any item subsequently changes, the publisher notifies the agency of the new URL and the agency updates the DOI record. Anyone then clicking on the DOI will be taken automatically to the new location.
The format of a DOI comprises two strings, separated by a ‘/’ character:
The first part of the DOI (the prefix) represents the original publisher and the second part (the suffix) represents the individual item. Publishers are free to define the format of their own suffix but the combination of the two parts must be unique. Once a DOI name has been assigned it will not change, even if a new owner takes responsibility for the item.
How to find the DOI for a piece of work
First of all, you should be aware that not all academic outputs are given DOI names. If the publisher has not registered to assign DOIs then an article will not be given one. Likewise, if the work is not available in electronic format then it is unlikely that it will have a DOI.
There is no complete index of DOI names but some registration agencies have a lookup tool for their own registered DOIs.
If you have the bibliographic details and want to know the DOI for an item then:
- CrossRef’s DOI lookup tool has several search options, depending on the bibliographic information you are able to supply (e.g. author and title only or full bibliographic details). The tool returns a DOI for the given search terms.
- DataCite’s DOI resolver or that of the International DOI Foundation is the tool to use. It takes a DOI name and returns the bibliographic details of the work.
You will also sometimes see DOI names listed on publishers’ websites and on bibliographic databases. Many of the library’s subscription databases such as ABI/Inform, ASSIA, Science Direct and Web of Science include the DOI as a standard element of an article’s metadata. If you know the DOI of your article then you can use it to speed up the process of entering the work into NECTAR.