Web usability and accessibility

Web usability is the ease with which users of a Web site are able to navigate it, perform a desired action and find the information they are seeking.
One important feature of the usability of a Web site is its accessibility. A Web site should be accessible by everybody irrespective of any physical or mental limitations, browser, screen resolution or personal settings. The Web Accessibility Initiative (WAI) of the World Wide Web Consortium (W3C) has issued guidelines to ensure that disabled users have equal access to the Internet. Besides, many countries have legal requirements to make Web sites accessible. It becomes a designer’s responsibility to adhere to these guidelines.
Users with visual impairment, hearing impairment, repetitive strain injury, and age-related conditions can use assistive technologies to interact with computers. These technologies include screen readers and refreshable Braille displays for visually disabled users and screen magnifiers for people with poor eyesight. A Web site should include text descriptions of images; for any audio components and text description or images. A Web site page layout should be designed to accommodate changes in font size and so on.
Accessibility must also take into account users other than those with disabilities, For example, users with mobile Internet connectivity, users with low literacy level and users in noisy environments.