The four principles

An innovation at the WCAG 2 respect to the WCAG 1 is the organization of the guidelines into principles. Accomplishing groups of guidelines you will success in a principle. The goal is to succeed in the 4 principles, as if any of them fails, users with disabilities will experience difficulties to use the website.

The 4 principles and their guidelines are:

The website must be “Perceivable”

Our website can be visited by people with very different types of perceptive preferences and needs, but also by robots (search engines, translators…). Our information and user interface components must address this handicap. We must give alternatives if a user cannot use one of her senses.

The website must be “Operable”

Webdesigners must be aware of the different devices the users can manage to use the website, so they must make the user interface components and navigation elements in a way that everyone can “operate” with it. E.g. Don’t limit user input to “mouse” or “pointers”.

The website must be “Understandable”

If our user don’t understand what we are talking about, or we make her feel lost, we have a problem. We must design our website, including the information and the user interface, in a friendly way.

The website must be “Robust”

This is the most-technology-dependant principle of all. It relies on the capacity of the website to be transmitted and interpreted by the user agents.
Remember that user agents are any software that retrieves and presents Web content, like browsers (Internet Explorer, Firefox, Safari…), media players (Quicktime, Realplayer, Windows Media Player…), plugins (e.g. those that help your browser perform specific functions), and, other programs, including assistive technologies (pointers, magnifiers…). So you can deduct that we must create our website thinking of this plethora of software that help in retrieving, rendering, and interacting with the Web content. We must be aware of the evolution of these technologies to adapt our website to their new capabilities.

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