The four principles of universally accessible websites (POUR)
So how do we make our website accessible? To help us navigate what's required, let's review four overarching principles, which go by the acronym POUR: Perceivable, Operable, Understandable, and Robust. These principals each cover a lot of ground and you'll notice some overlap, but they come together to outline what's needed to make your site universally accessible.
Perceivable
Everyone should be able to understand and use the content of your website with their senses. For many, perceiving our web content is primarily visual. However, for those using assistive technologies, the perception may be via sound or touch. To make our content more perceivable by all...
Text alternatives should exist for non-text content such as images and multimedia. Examples include closed captioning and transcripts for audio and video content, text descriptions of images and charts, and labels for interactive elements of your site (such as forms and search buttons).
Content can be presented in different ways. If we structure and markup our sites properly— from headings to lists — then our content will be correctly read aloud, enlarged, or adapted to meet the needs and preferences of different users.
Important content is easier to distinguish, see, and hear. Our goal here is to help people distinguish important information. For example, we want to ensure that color is not the only means of conveying information and that foreground and background color combinations provide sufficient contrast. Similarly, we want to ensure that our content is still readable when a person drastically enlarges the text and that our content flows well both on large and small screens.
Operable
This means anyone can successfully use all the interactive components of your website with multiple input devices ranging from keyboards to voice commands.
Your site needs to be functional from a keyboard and alternative input devices: Many of our users rely on the keyboard to interact with the Web or may not have the dexterity for fine mouse movements. This means your entire website interface — from forms to dropdown menus — need to be keyboard accessible; buttons, links, and other active interface elements need to be large enough to make them easy to activate by touch; and providing undo functionality if accidental activation is possible.
Users have enough time to read and use the content: Many sites rotate through content on a timer or timeout when an action does not take place quickly enough. However, some people need more time to read, use the content, type text, or operate controls. For these users it's critical we provide means of stopping or extending time limits, and pausing content.
Content does not cause seizures and physical reactions: Content that flashes at certain rates or patterns can cause photosensitive reactions, including seizures. Flashing content is ideally avoided entirely or only used in a way that does not cause known risks. If the flashing is unavoidable, include warnings and provide mechanisms to switch off animations.
Users can easily navigate, find content, and determine where they are: Well organized content helps users to orient themselves and to navigate effectively. For example, our pages need to have clear titles and be organized using descriptive section headings; our links need to have descriptive titles; and visual indicators should be used to show a user where they are located in a site, such as highlighting the current page in a menu..
Meeting this requirement makes the content easier to use for many people with a wide range of abilities using a wide range of devices. This includes content used on mobile phones, tablet computers, and self-service terminals such as ticketing machines.
Understandable
Understandable technology is consistent and predictable in its design and usage patterns, concise, and appropriate to the audience in its voice and tone.
Text is readable and understandable: Our content should be readable and understandable to the broadest audience possible. Examples include identifying the languages used on a web page; providing definitions for any unusual words and abbreviations; and using clearest and simplest language possible for the purpose. This helps assistive technology properly read content aloud and also helps people with different types of cognitive disabilities.
Content appears and operates in predictable ways: Many people can become disoriented or distracted by inconsistent site appearance or behavior. Thus, content, navigation, and interface components, need to appear in the same location on every page with the same labeling. With consistency, people can quickly learn the functionality and navigation provided on a website and to operate them according to their needs.
Users are helped to avoid and correct mistakes: Forms and other interactions can be confusing or difficult to use, which can result in user errors. We can program our pages to help users to avoid and/or correct mistakes. We can do this by including descriptive instructions, error messages, and suggestions for corrections. We can also provide opportunities for users to review, correct, or reverse their submissions if necessary.
Robust
If you do the above, your content becomes more compatible with current and future tools. It ensures your markup is compatible with different browsers, assistive technologies, and other user agents.
We often talk about compatibility with assistive technologies, such as screen readers, but we also need to keep our content usable for the future. For example, will your refrigerator be able to read a recipe and compare it to the contents of your refrigerator? If you recipe is marked up properly today, then it should be robust enough to succeed tomorrow.
Conclusion
These principles were developed to describe web accessibility, but they can be applied to almost any accessibility question. Technology providers must ensure that their users can perceive, operate, and understand their technology, and that the technology is robust enough to work across a spectrum of technologies, including assistive technology.
Recapping an important note... There are national standards that play a vital role in the requirements for each of these components. While some of these requirements are easy to meet, others require technical skills or advanced knowledge of how people use the Web. In this guide, we are focusing on the easier to meet requirements that you can fulfill now!
Credit: This content is adapted from Accessibility Principles by W3C Web Accessibility Initiative
Last updated