The two basic principles of accessible design of web sites are creating pages that transform gracefully and make content comprehensible to facilitate navigation through the site.

An accessible website is one whose content can be properly used by the largest possible number of users. The most important thing about a Web site accessible is to understand that people access the Web in very different ways.

Therefore, an accessible website should present the information so that users can access it regardless of the hardware and software they are using, and regardless of what physical and sensory skills used to interact with the computer.
Different ways to navigate

Know that not everyone uses to surf the Internet the same types of devices or the same way. Below are some examples of different types of users:

A user who uses a graphical browser with all the connectors or 'plug-in' installed. The browser is controlled mainly by the mouse and also occasionally with the keyboard (keyboard shortcuts and access to forms). This is the most common situation, but not the only possible.

A blind user may use a screen reader program to access the content that the browser Explorer. Listen to the text content of web pages through the soundcard for voice synthesis or Braille reading by a special device.

A user with visual impairment use a screen magnifier to enlarge the image and activate the largest font size available in the browser. If you can, turn off the colors defined on pages for display with the maximum contrast between text and background.

A user can have mobility impairments that prevent him from handling the mouse. However, handle all computer programs, including web browser, purely from the keyboard and using accessibility aids Windows 98 system.

Other users with slow Internet connections or who use older browsers or who do not have the latest connectors such as Flash and others. This is the case with some users accessing from other less developed countries or by using access stations in public places.

There are users who access the web using laptops 'palm-top' and mobile phones very reduced graphic displays.

Correct transformation

The first principle of accessible design is therefore to create pages that transform gracefully and whose content is well reproducible under different circumstances. We need to create pages that are accessible despite the mild cognitive impairment, physical or sensory users. We must also consider possible restrictions due to the place of access and technological barriers.

In this sense the text is always accessible. But this is not to create text-only pages without graphics or an attractive visual layout. HTML techniques exist to associate alternative text to each non-text element on the page.

In addition, multimedia graphics and used properly help to improve the accessibility of the website, they help to achieve another important principle of accessible design: understanding the content and easy navigation through the site.

Content understandable and navigable

This includes not only the use of clear and simple language , but also providing understandable mechanisms to navigate within each page and between pages of the website. By providing tools for navigation and orientation information in pages will maximize accessibility and usability of the website.

But as mentioned not all users can use visual cues such as image maps, background colors, adjacent frames or images that guide sighted users. Some users also lose contextual information when they can only see part of the page. This occurs when accessing the page with word for word speech synthesizers, braille or WAP phones or access by parties with small screens or screen magnifiers.