Sometimes we must accommodate several factors at once. The user with the manual dexterity may also have a visual disability brought up by age.
Accomodating users capabilities and limitations are rearly simple.
The World Wide Web Consortium considers the needs of users with a wide variety of disabilities, the W3C gives guidelines and success criteria for assessing accessibility.
For users with special needs, an accessible Web site provides perceivable contentoperable content components, understandable content and control and content compatability with other technologies.
Publishing a Web site makes it available to the world, but it is not possible to design for the world.
Certainly, there are generic commonalities across Web sites. Any Web site can have hyperlinks, controls, and information architecture. But, any Web site will also have unique features to meet the needs of its targeted audience.
Designers need to know the characteristics of the site's targeted audience to promote their success and satisfaction at the site.
They must also project future user characteristics. For example, the intended audience needs to include users with disabilities, even if none of the current users has a disability. Today's able user may have a disability tomorrow.
A Web site goal is to enable its users to experience success and satisfaction by accommodating each user attribute of the set of targeted users as well as the unique constellation of attributes defining each individual user.