A. Four principles of a well-coded page

You've now read multiple ways you can make your content more accessible to all readers, but what is the overall intent of accessibility encoding? According to the official Web Content Accessibility Guidelines (WCAG 2.2) all web content must be perceivable, operable, understandable, and robust — an acronym known as POUR in the digital accessibility community. Let's review these principals...


Perceivable states that all information is presented so it can be understood with multiple senses — sight, hearing, and/or touch. For example, if a person cannot clearly hear the audio of a video, closed captions allows them to see and read the text of what is being spoken.


All user interface components and navigation need to be operable with multiple input devices— be it mouse, touch, keyboard, voice, or specialized accessibility technology such as a tongue-controlled mouse. This ensures that all users, no matter a person’s motor abilities or dexterity, can readily interact with your content.

The interface has to communicate with the user about the status of interactive elements. For example, if a page has tabbed content, the site needs to describe to the screen reader which of the tabs are visible and which are hidden. Without this description, the screen reader simply cannot navigate these interactive features. This principle also relates to user interface aspects of your site such as the size of on-screen buttons being large enough that you can easily to touch them on your phone, or that a menu system can work with a keyboard as readily as with a mouse.


This states that the language of your content is readily understandable. This includes using language that is appropriate for your website’s readership, avoiding jargon, and providing instructions for online interactions that are easy to follow. Knowing your patrons is key. The language being used on a corporate library website would be quite different than a school library website.

Understandable also relates to your user interface having a predictable behavior. For instance, if you’re filling out an online form. The form should be able to clearly explain how to fill out the form, including when you’re making mistakes and how to correct them.


Your content and site infrastructure must be compatible with a variety of browsers, device types, and assistive technologies now and into the future. This is especially important as we move quickly into the internet of things — for instance just over 20% of the world now use smart watches.

In conclusion

There is certainly a Venn diagram with these principals. For instance, a well-designed study room reservation form that is easy to fill out on laptop or phone covers nearly the entire acronym. Think how hard it would be if the form didn’t tell you about your errors or how to correct them— that’s operable and understandable in combo.

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