Accessibility concerns the ease of access and usability of websites for people who have any type of disability. The word disability covers anything which makes it more difficult for a group of people to access or use Web content or functionality with the same ease as non-disabled users.
When considered in respect of website design disabilities can be broken down into four distinct categories:
- Visual - poor vision, blindness and colour blindness.
- Auditory - Deafness or partial deafness.
- Motor - Unable to use a mouse, problems with fine motor control.
- Cognitive - Learning difficulties, problems with concentration and focus.
Why make accessible sites?
The aim of designing accessible websites is to ensure that disabled users are able to interact fully with the website in the same manner as non-disabled users. Accessibility should be at the forefront of design considerations for a number of very good reasons, two of the principal ones being:
- Commercial - Studies have shown that as many as 20 percent of users have a disability - from a business perspective you cannot afford to alienate or ignore such a large group of your potential customers.
- Legal - Many countries including the US, the UK and Europe have laws in place which forbid discrimination against people with disabilities and many of these laws now have sections which relate specifically to website design and require positive action on the part of designers to ensure websites are accessible.
Making sites accessible
We will now have a brief look at the problems faced by people with disabilities when they use the Web and how these problems can be addressed in the site design.
VISUAL - Screen readers are programs which 'speak' the contents of the screen by converting the text into synthesised speech. Screen reader users can choose to have the screen read from top to bottom in its entirety or navigate between links, headings or frames using the tab key. This is done through the keyboard because it is virtually impossible to use a mouse if you can't see the cursor or the screen.
So to make websites accessible to screen readers there must always be a way of completing an action without having to use a mouse - when using mouse event attributes such as onmouseover or onmouseout an alternative means of accessing the content needs to be provided.
Screen readers have the limitation of only being able to speak text - they are unable to describe images or other information that is conveyed in a non-textual manner. In order to make this type of information available to screen readers a text alternative needs to be provided which they can read out. This can be done by using the alt attribute with the image to offer a description of the image and this should be done in the case of all images.
AUDITORY - Making sites accessible to users with full or partial deafness involves offering an alternative to any spoken content such as videos or audio clips. This can be done by adding captions to videos and providing a transcript of any audio or video clips used on the site.
MOTOR - One cause of motor control problems can be as a result of an injury causing spinal damage leading to partial or full paralysis.
Assistive technologies for users with these problems include head wands and mouth sticks, which people with limited or no use of their limbs can use to interact with a screen or keyboard. Designers should aim to make all content available through the keyboard and not purely with a mouse.
This also holds true for diseases such as Parkinsons Disease, arthritis and cerebral palsy which can make fine control difficult meaning that using a mouse effectively may be hindered. In addition to this users may become tired quickly due to the effort involved in trying to control a mouse or use a keyboard, designers should try and give visitors a means of skipping over long lists of navigation or content - such as links to content further down the page.
COGNITIVE - Designing for people with cognitive disabilities involves keeping things clear, simple and concise - something which should be part of the normal design process already. This group of users may not have the concentration or comprehension skills to deal with complex or lengthy pages of text but it should be pointed out that other visitors may not have the time or patience for such content. The modern Web user scans pages to extract the information required and designers should try to keep all their content to the point and as concise and relevant as possible.
W3C and accessibility
This is only a brief introduction to a very complex subject in order to make you aware of accessibility issues and show you some of the considerations that you need to take into account.
In addition to releasing recommendations for HTML and CSS the W3C also publish recommendations for accessibility in website design. Please visit the W3C Web Accessibility Guidelines 2.0 page to read the latest versions of the Web Accessibility Guidelines and for an in depth look at accessibility in web design.