To design something so that it is accessible means something specific. It means can all people, regardless of any impairment, interact with your content. For instance, how does someone who cannot use a mouse interact with your Web page? What if they cannot see? Does your site accommodate older populations and the issues they face?
To help answer those questions there are laws and standards which define:
- whose sites have to be accessible
- what type of content has to be accessible
- who needs to be able to access it
- how you determine what is and what is not accessible