In scientific journals, various persistent identifiers are used to ensure that articles, authors and resources are easily findable and citable over time.

Persistent identifiers are used in academia and science primarily to ensure reliable location, access, and citation of resources, such as journal articles, authors, books, datasets, and other digital objects. These identifiers have several key functions:

1. Establish Unique and Consistent Identity

Identifiers ensure that each object (whether an article, author, dataset, or publication) has a unique and consistent identity over time. This is especially important in a digital environment, where URLs and resources can change or be deleted.
Example: The DOI (Digital Object Identifier) assigned to a scientific article ensures that the same document can always be accessed, even if its location on the web changes.

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2. Facilitate Citation and Referencing

Identifiers enable researchers to accurately and efficiently cite the resources they use. A DOI, for example, allows an article to be cited consistently, regardless of changes in the publishing platform or URL.
Example: The use of a DOI in a citation, such as 10.1002/anie.202003574, ensures that anyone consulting that reference accesses the exact same article, even if there have been changes in the web page where it is hosted.

3. Ensuring Long-Term Access

Persistent identifiers provide a stable and reliable link to resources, ensuring that they are accessible over a long period of time, even if the content moves or changes location. This is especially relevant for digital preservation.
Example: Identifiers such as DOI or Handle ensure that an article or digital resource remains available, even if the original server or database changes.

4. Avoiding Confusion with Common Names

Some identifiers, such as ORCID, help to solve problems related to name ambiguity. Many authors may share similar or identical names, which can lead to confusion in citation and publication tracking. A unique identifier for each author makes it possible to track all of their works accurately.
Example: Two authors named “John Smith” may have different ORCIDs, such as 0000-0002-1825-0097, which makes it easier to distinguish their works.

5. Improve Search and Accessibility

Identifiers allow search systems (academic databases, digital libraries, repositories) to find resources more efficiently. Identifiers such as the ISSN for journals allow access to entire collections of scientific publications without ambiguity.
Example: An article published in a journal with ISSN 2042-6542 can be found quickly in systems that catalog that particular journal.

6. Promote Data Integrity

The use of identifiers ensures that referenced data and objects remain complete and verified over time, which promotes scientific integrity. This is crucial when data, such as research datasets, are used for analysis or reproducibility.
Example: A dataset in a repository can be identified with a unique identifier (such as a DOI or Handle), which ensures that data used in subsequent research are exactly the same.

7. Encourage Collaboration

Identifiers allow clear tracking of collaborations between authors, institutions or research projects. For example, the ORCID is used to associate an author with his or her publications and achievements, making it easier to connect with other researchers.
Example: A researcher may have multiple collaborations throughout his career, and his publications may be associated with his ORCID, which facilitates the tracking of his academic output.

Some of the most common persistent identifiers are listed below:

1. DOI (Digital Object Identifier) 2.

Description: The DOI is one of the most well-known and widely used identifiers in scientific publishing. It provides a persistent link to a digital object, such as a journal article, database or dataset.
Purpose: It ensures that the article is accessible, even if it is moved to a new location on the web. It is unique and remains constant over time.
Format: A DOI generally has this format: 10.xxxx/xxxxx, where “10” is the prefix indicating that it is a DOI and the rest is a unique identifier of the object.
Ejemplo: 10.1002/anie.202003574

2. ORCID (Open Researcher and Contributor ID).

Description: The ORCID is a unique identifier for authors and contributors in research. Its purpose is to distinguish researchers with similar names and to persistently associate their work with their identity.
Purpose: To facilitate the correct attribution of papers and collaborations, avoiding confusion between authors with common or variant names.
Format: A unique number assigned to each researcher, for example: 0000-0002-1825-0097.
Example: A specific ORCID could be https://orcid.org/0000-0002-1825-0097.

3. ISSN (International Standard Serial Number)

Description: The ISSN is a unique identifier used for periodicals, such as scientific journals, newsletters and newspapers.
Purpose: It facilitates identification and access to periodicals, especially in libraries, databases and repositories.
Format: An ISSN is presented as an eight-digit numeric code, divided into two groups of four digits, separated by a hyphen, for example: 1234-5678.
Example: 2042-6542.

4. ISBN (International Standard Book Number)

Description: Similar to the ISSN, the ISBN is used to identify published books, book chapters or monographs. Although it does not apply directly to journal articles, it is relevant when publishing compilations of scholarly articles or books.
Purpose: To ensure unique and persistent identification of books and other monographic works.
Format: A 10- or 13-digit number. Most recent books have a 13-digit format, for example: 978-3-16-148410-0.

5. Handle

Description: The Handle system is a persistent identification system used primarily for digital objects and scholarly resources, similar to the DOI, but more general in use.
Purpose: To ensure the persistence of links to digital objects, regardless of the platforms on which they are located.
Format: A unique identifier assigned to a digital object, for example: hdl.handle.net/10.1000/xyz123.
Example: hdl.handle.net/10.1000/182.

6. ARK (Archival Resource Key)

Description: ARK is another type of persistent identifier used for preservation and access to digital objects in long-term repositories.
Purpose: Ensures that resources remain accessible over time, even if the location of the files changes.
Format: Similar to a DOI, with the structure: ark:/12345/xyz.
Ejemplo: ark:/13030/tf3489n5gq.

7. PURL (Persistent Uniform Resource Locator).

Description: The PURL is an identifier that redirects to an online resource, similar to a normal URL, but with the advantage that its destination can change without losing the persistent link.
Purpose: Provides a link that always redirects to a specific resource, even if the object's URL changes.
Format: A PURL has the format http://purl.org/xyz, where “xyz” is the unique identifier.
Example: http://purl.org/dc/elements/1.1/title.

8. URN (Uniform Resource Name)

Description: The URN is a type of persistent identifier that aims to provide a unique and persistent identification for information resources without depending on their location.
Purpose: Its use is aimed at long-term preservation of resources, regardless of physical locations or URLs.
Format: A URN has the form urn:namespace:identifier.
Ejemplo: urn:nbn:de:101:1-20200310.

9. LSID (Life Science Identifier)

Description: An LSID is a persistent identifier used to describe objects in biology and the life sciences, such as species, genes, or publications.
Purpose: Ensures that references to biological resources are accurate and persistent, regardless of changes in the location of the data.
Format: An identifier having the form lsid:urn:lsid:example.org:12345.
Example: lsid:urn:lsid:taxonomy.example.org:12345.

10. CrossRef (for citing and linking articles)

Description: CrossRef is an organization that provides DOIs to scholarly articles and other digital objects. It also facilitates citation linking through its metadata database.
Purpose: It is used to facilitate the proper citation of articles and resources in scholarly publications, ensuring that citations are verifiable and associated with the correct objects.
Example: The use of CrossRef generally involves the inclusion of a DOI as a persistent identifier for an article.

Conclusion

These persistent identifiers allow scientific articles, data, authors, and publications to remain accessible and reliably cited, regardless of changes in URLs or resource locations on the web. Each has a different purpose and format, but all serve the function of ensuring the long-term persistence and accessibility of scholarly resources.