Link categories delineate the connections between multiple web pages and can clarify the purpose of specific hyperlinks within a webpage. Properly defining link categories is crucial for Search Engine Optimization (SEO) as search engines utilize this information to better comprehend the content.By specifying appropriate link categories in HTML markup, other web services such as social media platforms, assistive technologies, and language translation tools can also benefit.The attribute is employed to define link categories. An example of setting a link category on an HTML element is provided below:Multiple link categories can be assigned. Simply separate them with spaces.When linking to a webpage with the categories and , the following approach should be taken:This guide will focus on hyperlink link categories. There are 12 link categories that can be applied to hyperlinks. The following table lists possible link categories and their corresponding destinations:
Link Category
Destination
alternate
an alternative viewing method for the webpage.
author
additional information about the webpage’s author (or specific sections).
canonical
a permalink or SEO-friendly URL.
help
content aiding users with a specific part of the webpage.
license
the copyright license of the webpage’s primary content.
nofollow
a webpage that is not endorsed.
Or a webpage linked primarily for commercial gain.
noopener
a webpage that should not disclose the click origin.
preload
a resource that the user is likely to need. The browser should fetch and cache this resource before the user requests it.
search
a search interface for the webpage.
stylesheet
the keyword or category of the webpage.
next
the subsequent webpage in a series.
prev
the preceding webpage in a series.
We will delve deeper into each link category and provide use cases for each.The link category directs to alternative viewing methods for the webpage.You may have the webpage available in a different format, such as PDF or a printer-friendly version. Using the link category informs browsers: “This is the same content, just in a different format.” The attribute can also be used in this scenario.In the following code snippet, we specify that both hyperlinks point to alternative representations of the webpage. The first link points to a PDF version of the webpage, while the second link points to a downloadable ZIP file containing the PDF.The link category can be used to reference language translations of the current page.For enhanced meaning, the attribute can be used to define the language of the referenced webpage.The link category informs the browser that the hyperlink leads to author-related information.Many times, only certain sections of a webpage are authored by the author. In such cases, the link category should reference the author of the contents within the parent element. For example, on news websites, journalists may write the main content, while other elements like comments are authored by readers. This situation can be marked up as follows:The link category indicates that the hyperlink points to a permalink.Below are examples of blog posts linking to permalinks:The link category directs to content that offers helpful information. When using the link category, the referenced content should be context-specific. In other words, the link should direct to specific help information about the parent HTML element containing the hyperlink. An example is provided below:In this case, the link category refers to a webpage that provides helpful information about the parent element.The link category can be used on links pointing to the licensing terms of the webpage’s primary content.This link category should be used within tags to define which parts of the webpage are covered by the license. The license will only apply to the contents of the parent element. The following markup represents three images:However, only one of them is licensed under the Creative Commons Public Domain Dedication (CC0).The link category is used to indicate that the link on your webpage is not endorsed or that it is present due to commercial compensation.This link category can be used on user-generated links, such as links in wiki entries, blog post comments, or answers on Q&A sites like StackOverflow. These links were added to the webpage by someone else.As the website owner, you may not always be able to support or endorse the links shared by users on your website. In this case, the link category informs search engines that the website owner may not have reviewed the link and/or does not endorse it.The link category can also be used for paid links, typically advertisements. If the website owner has added a link to a webpage primarily due to a commercial/for-profit relationship with the linked page, defining the link as a is the appropriate action.By design, the link category is used on hyperlinks where, upon clicking, the destination webpage is not informed that the user came from your webpage. However, it is uncertain how many browsers currently implement the specifications of this link category.When clicking on a link with the link category, the browser should not include the HTTP header, which can be used by website owners to track user origin.The link category should be used when pointing to external resources the user is likely to need. It instructs browsers to fetch and cache the resource before the user clicks on the link. For example, you may have an image gallery.When the user clicks on an image, you can display a larger version. To enhance the user experience, you can instruct the browser to cache the larger image version so it’s ready when the user wants it.The link category points to a search interface for the webpage. This search interface could be an in-page search form or another webpage capable of searching the current page and related pages.Here’s an example of linking to a search form within the page:The link category can be used to point to the category or keyword matching the content of the webpage. For instance, this guide is categorized under the HTML category.By using the link category, I can inform browsers that this page is part of the HTML category, allowing search engines to identify similar articles during crawling.The link category points to the subsequent webpage in a series, while the link category points to the previous page.For instance, if we have a four-part article series, we are currently on the second article. At the end of the articles, we have a list of links pointing to other articles in the series. We can mark this up as follows:Keep in mind that link category keywords are not case-sensitive. While the common convention is to use all-lowercase for HTML markup, this is your markup, so you should use whatever works best for you.In the following example, all hyperlinks are valid:In addition to the covered link categories, there are two other link categories not discussed here: and . They cannot be used on hyperlinks. Microformats link categories can also be utilized. These link categories are not officially part of the W3C standards but are supported by search engines and browsers.This guide is based on the HTML5 W3C Recommendation for link categories.
Designing the Perfect Hyperlink
CSS Link Pseudo-classes
How to Find and Remove Broken Links in Your Website
Ultimate Guide to Microformats: Reference and Examples
