Documentation

The importance of metadata

Citations are the backbone of scholarly communication, allowing researchers to point to the evidence for their assertions, and to provide credit to the originators of ideas. As content has moved online, researchers have grown to expect to be able to simply click on citations and follow links to the cited content online. If these citations broke at the same rate and in the same way as normal web links, it would only be a matter of years before the the system started to crumble. It would also mean that links to research outputs would break and adversely affect everyone.

To solve this problem, we built a common infrastructure that can be used by all. It allows citation linking using Digital Object Identifiers (DOIs) between research produced by different organizations (without the need for individual agreements between them). This ensures that citation links are persistent - that they work over long periods of time. However, there is no purely technical solution to the problem of broken links on the web; Crossref members have to keep these links updated, along with rich metadata that everyone in the scholarly ecosystem relies on.

It’s all about the metadata

The collective power of our members’ metadata is available to use through a variety of tools and APIs—allowing anyone to search and reuse the metadata in sophisticated ways.

Members register content with us to let the world know it exists. They send us information called metadata which we collect and store in a standard way. The metadata includes a Digital Object Identifier (DOI) in each record, which links to the content even if it moves to a new website. We make this metadata openly available via our APIs, which means people and machines can incorporate it in their research tools and services. Metadata does not include the full-text of the content itself. While we collect and distribute metadata, we do not change members' metadata. Learn more about the metadata each member is depositing with us using our Participation Reports.

Manuscript tracking services, search services, bibliographic management software, library systems, author profiling tools, specialist subject databases, scholarly sharing networks - all of these (and more) incorporate scholarly metadata into their software and services. They use our free APIs to help them get the most complete, up-to-date set of metadata from all of our publisher members. And of course, members themselves are able to use our free APIs too.

Metadata users and uses: metadata from Crossref APIs is used for a variety of purposes by many tools and services

DOIs and persistent identifiers

A persistent identifier is an ongoing, long-lasting digital reference to something. In the scholarly information world, a Digital Object Identifier (DOI) is the type of identifier most commonly used for research objects such as articles, grants, books, datasets, protocols, figures, and more. There are several organizations who register DOIs as agents of the DOI Foundation (DF), and Crossref is one of them. Most DF agencies are in the scholarly information world like us, such as CNKI, JaLC, DataCite, KISTI, and mEDRA. But some agencies register DOIs for entirely separate purposes such as supply chain management in the building and construction industry, or for tracking movies and merchandise in the entertainment industry.

At Crossref, every metadata record that our members register for their content needs to have a unique DOI attached to it, both as a container for that record and as a locator for others to use. A DOI does not signify any value or accuracy of the thing it locates; the value lies in the record’s metadata which gives context about the object (such as contributors, funding bodies, abstract/summary) and enables connections with other entities (such as people (e.g. ORCID) or organizations (e.g. ROR)).

Here’s what a Crossref DOI looks like:

The structure of a DOI: resolver, prefix, suffix

Once a DOI has been registered with us, it should always be used for the same content. Even if the content moves to a new website or a new owner, the same DOI should continue to be used. Though the DOI never changes, its associated metadata is kept up-to-date by the relevant Crossref member.

Page owner: Patricia Feeney   |   Last updated 2021-April-21