Website Accessibility – Understanding the guiding principles

Is website accessibility on your To Do list but don’t know where to start? Here’s an article explaining the 4 guiding principles behind WCAG, the Web Content Accessibility Guidelines that form the basis of legal compliance in the UK.

In this article I’ll cover the 4 principles that are behind WCAG, the web content accessibility guidelines set out by the W3C (World Wide Web Consortium). Please see the first article for more information about the W3C and their role in setting out the guidelines.

The 4 guiding principles are:

  1. Perceivable
  2. Operable
  3. Understandable
  4. Robust

Let’s go over each of these in turn.


This means that when people visit your website they must be able to access all the information regardless of their abilities. For example if a visually impaired person visited your website the information must be fully available via another sense like hearing so if they choose to use assistive technology like a screen reader they are still able to perceive the information.


This means that your website will be usable regardless of the input devices used to interact with it. For example, a person with fine motor skill issues may choose to use only their keyboard and not a mouse – your website should be navigable and interactable using only a keyboard just as well as it would be using a keyboard/mouse combination. There are other types of input devices, like screen readers, puff-suck switches etc, that should also be taken into consideration.


This principle covers a range of requirements, some of which are: interface design, error feedback and complexity of language. In essence what this principle is getting at is that your website, at every level whether it is the interface visitors interact with or the language used, must be as understandable as possible. For example, an established design principle for text links on a web page is to underline them (and make them blue if you really want to get traditional) – although you don’t have to do this, if you do, fewer people will have to work out what the links on your website look like. This may seem a small deal to most but this starts to take people who suffer from anxiety into consideration (after all the goal of accessibility is inclusion) – they may get anxious when the structure of your website isn’t obvious. Another example is people who suffer from visual impairments. If the colour contrast of text on the background of your site is poor (think light grey text on a white background) then it becomes difficult to read for many people e.g. adults start to lose vision from the age of 40 so if the over-40s make up part of your target market you’re likely to be excluding many people who haven’t taken visual corrective measures from using your website.


Robustness refers to ensuring your website and its content is compatible with a variety of technology used to access it i.e. browsers and assistive technology like screen readers and braille terminals. Collectively, these are known as ‘user-agents’ and the idea is to allow as many of them as possible, especially assistive technology, to successfully access the information on your website. New technology is always being developed so following the conventions set out in the guidelines means new technology developers have a standard they can meet when creating new ways of accessing websites.

Hopefully this post has given you an idea of where to start with accessibility for your website. If you require some guidance please contact me on this site or contact me on LinkedIn (opens in a new tab).

Chandesh Parekh

Chandesh Parekh

A website accessibility / inclusivity consultant, web developer and reputation marketer, Chandesh has been professionally immersed in the world wide web for over 20 years. Chandesh on LinkedIn (opens in new tab)