Four principles

WCAG (Web Content Accessibility Guidelines)

WCAG stands for Web Content Accessibility Guidelines and is a recommendation of the World Wide Web Consortium (W3C) for the design of accessible websites.

The International Web Content Accessibility Agreements describe common standards to help content creators and authors design digital content, such as websites, web applications, and other digital technologies, which is easy to access by everyone.

The guidelines are grouped into four principles: Perceivable, Operable, Understandable and Robust.

The four principles are an approach to classify and systematize website accessibility. Many of the challenges faced by people with disabilities can be described using one of the four principles. Yet, the four principles overlap. They cannot always be strictly separated from each other and they often complement each other.

Four principles and impairments

The four WCAG principles describe a variety of measures or guidelines that can be used to make portal and application pages accessible to people with disabilities. They cannot be assigned on a one-to-one basis, instead they regularly overlap. For example, measures to overcome barriers related to vision and hearing are listed under the "Perceptible" principle.

Brief description of the four principles

Perceivable

"Information and components of the user interface must be presented to users in such a way that they can perceive them." (WCAG)

The "Perceptible" principle is about users being able to perceive information and components on portal and application pages with at least one of their senses. For example, if a user is blind, they should be able to use screen readers to hear information instead of seeing it. This is mainly achieved by storing text alternatives for graphics or, if necessary, buttons, which are then read out by screen readers.

For users with impaired vision, it is critical that color contrasts, font sizes, line spacing, and character spacing be sufficiently large. For people with red-green deficiency, it is important to use colors that you can distinguish.

Operable

"Components of the user interface and navigation must be operable." (WCAG)

The "usability" principle is all about ensuring that a user can navigate through portal and application pages without any problems. A well-designed page structure with a clear menu is crucial for this. To operate portal and application pages, the user must not be required to take any action that they cannot perform.

The main measure in connection with operability is the ability to access any content with the keyboard. Additionally, the page can be navigated by keyboard, allowing the user to move from one area of the page to the other without any limitations.

Understandable

"Information and operation of the user interface must be understandable." (WCAG)

Language plays a central role in the "understandable" principle. As a rule,"simple language" should be used. On the level of language, there are no Intrexx-specific or technical aspects to consider in regard to this principle. These are exclusively "editorial" activities.

The situation is somewhat more technical in the case of error messages, which should provide appropriate information for the correct handling of an application. At the same time, such error messages must be accessible to screen readers. They should also be displayed for a sufficiently long time.

However, the principle of "understandable" also includes non-linguistic aspects. For example, the navigation should be consistent and thus comprehensible.

Robust

"Content must be robust enough to be interpreted by a wide range of user agents, including assistive technologies." (WCAG)

The "Robust" principle is about technical aspects. This principle is presented very succinctly by WCAG. Essentially, it involves ensuring that portal and application pages are compatible with future technologies, especially assistive technologies. Among other things, the correct syntax of the source code plays a decisive role here.

Principles, guidelines and success criteria

The four principles of accessibility are described in more detail through guidelines. Simultaneously, the guidelines already provide information on how the principles and their goals can be implemented on portal or application pages. There are 13 guidelines in total.

The following chart gives you an overview of the four principles and which thirteen guidelines are assigned to them.

Finally, each guideline has been given success criteria. These success criteria list numerous specific conditions that must be met for the particular principle or guideline to be implemented on the webpage.

Success criteria for the "Distinguishable" guideline ("Perceptible" principle) are, for example:

  • Use of Color

  • Audio Control

  • Contrast (Minimum)

  • Resize text

  • Images of Text

  • Contrast (Enhanced)

  • Low or No Background Audio

  • Visual Presentation

  • Images of Text (No Exception)

  • Reflow

  • Non-text Contrast

  • Text Spacing

Priority levels - A, AA, AAA

Success criteria have different levels of priority. For example, the success criterion "Use of color" has priority level A (lowest priority), "Change text size" priority level AA (medium priority) and "Contrast (increased)" priority level AAA (highest priority).

A Level A page must meet all the requirements of that level. For priority level AA, the requirement of levels A and AA must be met and for priority level AAA, the requirements of levels A, AA and AAA must be satisfied. The fulfillment of level AAA is not taken as a general condition for the entire website, as some content cannot fulfill every requirement of this level.