Contents
What are ARKs?
ARKs (Archival Resource Keys) are high-functioning identifiers that lead you to things and to descriptions of those things. For example, this ARK,
https://n2t.net/ark:/67531/metadc107835/
gets to a dissertation, and adding a '?' to the ARK gets you to its description:
https://n2t.net/ark:/67531/metadc107835/?
What's an identifier?
On the internet, an identifier is a URL, or part of a URL. For example, this basic ARK identifier,
is part of two different URLs (Uniform Resource Locators), also known as web links or web addresses:
https://gallica.bnf.fr/ark:/12148/btv1b8449691v/f29
https://n2t.net/ark:/12148/btv1b8449691v/f29
ARKs are especially good at being persistent identifiers.
What's a persistent identifier?
The average lifetime of a URL has been said to be 44 days. At the end of its life, a URL link breaks, which means it gives you the dreaded "404 Not Found" error. As irritating as it is – and most of us have seen it happen – it's a disaster for libraries, archives, museums, and other memory organizations. A persistent identifier (sometimes abbreviated to PID) is an identifier that in principle will continue to work far into the future, even as things move between websites. Normally when things move, we're burdened with broken links and having to learn to use their new URLs (links), and that's where identifier resolvers come in.
What's a resolver?
A resolver is a website that is especially good at forwarding an incoming identifier (the one originally advertised to users) to whatever website is currently best suited to deal with it. To make it work, the hostname of the resolver itself is carefully chosen so that it never has to be changed. Memory organizations, some of them centuries old, tend to have website hostnames that are especially stable as resolvers. Other well-known resolvers include n2t.net, identifiers.org, doi.org, handle.net, and purl.org.
How do ARKs differ from DOIs, Handles, PURLs, and URNs?
These are all major kinds of persistent identifiers. The short answer is that aside from URNs, ARKs are the only mainstream, non-siloed, non-paywalled identifiers. Over 500 registered organizations have created an estimated 3.2 billion ARKs in the world, and no one has ever paid for the right to create them.
Would you expand upon that answer?
These identifiers all work fine with forwarding by resolvers. They also have very similar structure. In these hypothetical examples,
https://n2t.net/ark:/99999/12345
https://doi.org/10.99999/12345
https://handle.net/10.99999/12345
https://purl.org/99999/12345
https://n2t.net/urn:99999:12345
there's the protocol (https://) plus hostname, followed by the Name Assigning Authority (99999 or 10.99999), which is the organization that created the identifiers. Finally there's the name, or local identifier, that it assigned (12345).
Here are some ways in which ARKs, DOIs, Handles, PURLs, and URNs differ. This is by no means an exhaustive list.
- When (not if, since all things pass) the https:// protocol and the hostname cease to exist, only ARKs and URNs will still indicate the kind of identifier that remains.
- To create DOIs, Handles, and PURLs, you are required to use their respective resolvers. There are no such silos with ARKs and URNs, for which you can use your own resolver.
- To create DOIs and Handles, you are also required to pay a membership fee and per-DOI charges. There are no such paywalls for ARKs, PURLs, and URNs.
- It is hard to generalize how people use these identifiers. DOIs, for example, used to be known primarily as identifiers for scientific and scholarly publications, with a mature community and service offering around "Crossref DOIs", but since 2013 enough new assigners have joined that it is hard to make generalizations about DOIs.
- Although you can use your own or a vendor resolver for your ARKs, all ARKs can be resolved via n2t.net. Thus n2t.net is the closest thing to a "global ARK resolver".
- There is no single global resolver for URNs.
- Strong principles of openness prevented n2t.net, which was built for ARKs, from becoming just another DOI/Handle/PURL-type silo. As a result, the "global ARK resolver" also resolves DOIs, Handles, PURLs, and URNs, along with 600 other kinds of identifier. This anti-silo principle is exemplified by micro-service tools such as "noid", also built for ARKs, that are routinely used by organizations to mint Handles.
I've heard of ORCIDs and UUIDs – where do they fit in?
Those are special kinds of persistent identifiers. ORCIDs identify researchers, and they link to research works using ARKs, DOIs, etc. ORCIDs look like
https://orcid.org/0000-0001-7604-8041
UUIDs are globally unique, 37-character strings that are easy for software to generate but only become usable as web addresses when made part of a URL, for example, in this ARK:
https://n2t.net/ark:/65665/3c2e39526-e0c3-41ae-be4f-07558a9458eb
