What are the four principles of content accessibility?

Content accessibility is one of the most important parts when developing a website. But to be accessible, you must put disabled people at the centre of the process.

When people visit your website, they’re all using different devices. Some will be using operating systems, browsers, plugins, screen readers, and assistive technology. And when they arrive at your site, they will be expecting it to work with the tech they are using.

If your website does not meet the needs of this audience, you are alienating people from your site.

With 14.6 million disabled people in the UK alone, that is a massive audience not to include. You will need to ask questions that perhaps you’ve never asked until now.

When you look at your website, would you say it’s accessible to the following?

  • people with sight loss, low vision or who use a screen reader
  • those with colour deficiencies or colour blindness
  • people with hearing loss or who are deaf
  • those with limited dexterity
  • those with learning difficulties, like dyslexia, those who are autistic or have ADHD

The four core principles can help you understand content accessibility better. The Web Content Accessibility Guidelines (W3C), or WCAG for short, are built around these principles. WCAG sets the standard for accessibility every website needs to meet. The AA standard is considered the legal minimum.

The principles use the acronym POUR, which stands for:

  • Perceivable
  • Operable 
  • Understandable
  • Robust 



All communication relies on the senses. The most relevant senses to web content are:

  • sight
  • hearing
  • touch

If people cannot perceive your content, you have an inaccessible website. Yet, many sites still contain content that some people cannot perceive.

The content on your website needs to be perceivable to at least one of the senses.

For example:

If a screen reader comes to your website, are there alternatives for non-text content? Like alt-text descriptions for images. Or a video or audio file explaining an infographic or graph.

If someone with hearing loss is on your website, are there captions on your videos? Or transcripts for audio content that people can access rather than listening.


There are many different ways that people might interact with your website.

For example, can someone just using their keyboard see which element they’re on? Can they click on links and buttons?

When it comes to understanding the needs of your audience, do not assume that everyone uses a mouse or a keyboard. Someone with a visual impairment might use speech recognition software.

If you want to connect with all your customers, people need to be able to operate your website easily. Regardless of the methods or forms of technology they use.


Is the content on your website easy to read and understand?

People have a range of cognitive abilities. People with dyslexia can struggle with reading and lots of text. Others on the autism spectrum, can struggle with metaphorical and figurative language.

Using clear and direct language that is easy to understand is important. This might mean:

  • using shorter sentences, Hemingway App can help
  • removing jargon or complex language, or including explanations with them
  • breaking up long paragraphs into shorter sections
  • using headings to break up long pages
  • using short bullet points


Is your website built in a way that is compatible with the technology of your audience? Can visually impaired people use a screen reader to access the content on your website?

Your website needs to be interpreted by a wide variety of assistive technologies to be accessible. This includes reasonably outdated, current and anticipated tech standards and assistive technology.

Add POUR to your process

If you want to make POUR a core part of your business, focus on what disabled people need. By doing so, you will provide an inclusive experience.

Also make sure POUR is part of your process. Do not try to apply it at the end. It’s much harder and will take more time and money.

Designing for diverse audiences is better for business and will help you reach more people.

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