Our definition of website accessibility
"Website accessibility" means making your site usable by the widest range of users.
The emphasis is on people with physical, sensory or comprehension difficulties - for example, deafness, colour-blindness and dyslexia.
Making sites accessible to the fullest degree usually requires investments in development time and restrictions on visual design.
It also demands specialist knowledge on behalf of the design and development teams.
Therefore, while accessibility is clearly important, concessions to budget and design usually have to be made.
The accessibility of this site
We addressed many fundamental accessibility issues by choosing a website management system well-known for its accessibility-friendly code: CMSMadeSimple.
Features include tags designed to work with screen-readers for blind users.
We also applied accessibility conventions as we inserted the content.
For example, graphics are accompanied by ‘alt' tags and links by 'title' tags (so when you roll over them, you will see a description - try it) and pages are enhanced with meta-tags (key words describing the page's content).
Also we made the section names and headlines comprehensible to the broadest audience.
Our interpretation of the law
The law in England and Wales - specifically, Section III of The Disability Discrimination Act - is this: companies have to make "reasonable adjustments" to enable the disabled to use their websites.
Theoretically if you operate a website which is not accessible to people of all abilities, you can be sued.
The truth is that few websites reach this gold standard. In practice what it means is that you should aim to apply the Priority 2 standard of the W3C Web Content Accessibility Guidelines 1.0, which is the EU-recommended level of compliance.
If you want to observe best, emerging practice, you should apply WCAG 2.0 standards (currently in draft).
Note that accessibility is not to be confused with "usability" which is defined by schools of thought and good practice, not by legislation.