Users experiencing low vision, dyslexia, and certain cognitive disorders may wish to increase the space between letters, words, and lines in order to more easily understand the content of your website.
For content implemented on your site using markup languages, users should be able to make the following changes to text settings without loss of content or to functionality, where the markup language supports these text style properties:
This rule is not asking you to make these changes to your site. As the wise and benevolent ruler of your personal 'domain' (get it?), it's your responsibility that users can alter your text settings easily and efficiently.
If you don't take into account that users may wish to alter spacing on your page, you can often run into issues where text is cut off, such as in the example included here:
Or where it overlaps other text, like the example pictured here:
[Source: same as previous image]
Keep these considerations in mind when authoring your site to avoid such problems.
This rule applies only if the markup language you're using to author your site supports users overriding text to meet the specifications outlined earlier. If you're using Cascading Style Sheet/HTML technologies, for instance, then this rule applies. Plugins would require a built-in mechanism for altering text styles.
Notable cases where this rule would not apply include: