Web Content Accessibility Guidelines

WCAG1: Perceivable Success Criteria

Information and user interface components must be presentable to users in ways they can perceive. This means that users must be able to perceive the information being presented. User agents, like screen readers, require clearly defined HTML elements within a structured web page. The Banner, Navigation panel, Main section, and Footer are visually perceivable on a standard computer screen, but not necessarily on a screen reader device.

1.1 Text Alternatives

The intent of WCAG 1.1 Text Alternatives Success Criterion is to make information conveyed by non-text content, such as images, accessible through the use of a text alternative. Text alternatives make information accessible because they can be rendered through any sensory modality. Such as visual, auditory or tactile to match the needs of the user.

A person who cannot see a picture can have the text alternative read aloud using synthesized speech.
A person who cannot hear an audio file can have the text alternative displayed for reading.

1.2 Time-based Media

The intent of WCAG 1.2 Time Based Media Success Criterion is to make information conveyed by prerecorded audio-only and prerecorded video-only content available to all users.

A video with no audio is a silent movie, and a written descriptive video transcript will provide an equivalent to what is presented visually.
For prerecorded video content, authors have the option to provide an audio track, which will serve as an alternative equivalent to the video. This approach would not only make the video content accessible to blind users, but also make it easier for those with cognitive, language and learning disabilities to understand the content because it would provide parallel presentation.

1.3 Adaptable

The intent of WCAG 1.3 Adaptable Success Criterion is to ensure that information and relationships that are implied by visual or auditory formatting are preserved when the presentation format changes. Sighted users perceive structure and relationships through various visual cues.

Headings are often in a larger, bold font separated from paragraphs by blank lines;
List items are preceded by a bullet and perhaps indented;
Paragraphs are separated by a blank line;
Items that share a common characteristic are organized into tabular rows and columns;
Form fields may be positioned as groups that share text labels;
A different background colour may be used to indicate that several items are related to each other;
Words that have special status are indicated by changing the font family, or bolding, italicizing or underlining them; and so on.

1.4 Distinguishable

The intent of WCAG 1.4 Distinguishable Success Criterion is to ensure that all users can access information that is conveyed by colour or audio differences.

Playing audio automatically when landing on a page may impact screen reader users. Individuals who use screen reading software can find it hard to hear the speech output if there is other audio playing at the same time. Therefore, it is important that the user be able to turn off the background sound or control the volume level.
If the information is conveyed through colour differences in an image the colour may not be seen by users with colour deficiencies. Providing the information conveyed with colour through another visual means ensures users who cannot see colour can still perceive the information.
The intent of this Success Criterion is to provide enough contrast between text and its background so that it can be read by people with moderately low vision, who do not use contrast-enhancing assistive technology.

WCAG2: Operable Success Criteria

All web page elements must be operable by a keyboard, speech input, and other non-mouse devices. Some of the Java scripts may not be keyboard accessible, and preventing non-mouse users from performing some functions.

2.1 Keyboard Accessible

The intent of WCAG 2.1 keyboard Accessible Success Criterion is to ensure that, wherever possible, content can be operated through a keyboard or keyboard interface, so an alternate keyboard can be used.

When content can be operated through a keyboard, or alternate keyboard, it is operable by people with no vision, who cannot use devices like mice that require eye-hand coordination.
As well as by people who must use alternate keyboards or input devices that act as keyboard emulators. Keyboard emulators include speech input software, sip-and-puff software, on-screen keyboards, a variety of assistive technologies and alternate keyboards.

2.2 Enough Time

The intent of WCAG 2.2 Enough Time Success Criterion is to ensure that users with disabilities are given adequate time to interact with web content whenever possible.

People with disabilities such as blindness, low vision, dexterity impairments, and cognitive limitations may require more time to read content or to perform functions such as filling out online forms.
If web functions are time-dependent, it will be difficult for some users to perform the required action before a time limit occurs. This may render the service inaccessible to them.
Providing options to disable time limits, customize the length of time limits, or request more time before a time limit occurs helps those users who require more time than expected to successfully complete tasks.
Avoid distracting users during their interaction with a web page; such as moving, blinking, scrolling and auto-updating content.
Allow users to turn off content updates, except in emergencies. This allows access by people with cognitive limitations or attention disorders by enabling them to focus on the content.
It also allows users who are blind or have low vision to keep their "viewing" focus on the content they are currently reading.

2.3 Seizures and Physical Reactions

The intent of WCAG 2.3 Seizures and Physical Reactions Success Criterion is to allow users to access the full content of a site without inducing seizures due to photosensitivity.

Individuals who have photosensitive seizure disorders can have a seizure triggered by content that flashes at certain frequencies for more than a few flashes.
Some users experience distraction or nausea from animated content. For example, if scrolling a page causes elements to move (other than the essential movement associated with scrolling) it can trigger vestibular disorders. Vestibular (inner ear) disorder reactions include dizziness, nausea and headaches.
Another animation that is often non-essential is parallax scrolling. Parallax scrolling occurs when backgrounds move at a different rate to foregrounds. allow users to prevent animation from being displayed on web pages.

2.4 Navigable

The intent of WCAG 2.4 Navigable Success Criteria is to provide ways to help users navigate, find content, and determine where they are.

A sighted user can ignore repeated content either by focusing on the center of the screen, where main content usually appears, or a mouse user can select a link with a single mouse click rather than encountering every link or form control that comes before the item they want.
Likewise, it is important to allow people who navigate sequentially through content with a keyboard more direct access to the primary content of the web page. Such as skipping repeated blocks of content, like navigation links, headings, graphical images, and advertising frames.
Help users find content and orient themselves within the website by ensuring that each web page has a descriptive title. Titles identify the current location without requiring users to read or interpret page content.
Ensure that when users navigate sequentially through content, they encounter information in an order that is consistent with the meaning of the content and can be operated from the keyboard. This reduces confusion by letting users form a consistent mental model of the content.
Help users understand the purpose of each link so they can decide whether they want to follow the link. Link text that is as meaningful as possible will aid users who want to access more information.
Also, the intent of this Success Criterion is to help users understand what information is contained in web pages and how that information is organized. When headings are clear and descriptive, users can find the information they seek more easily, and they can understand the relationships between different parts of the content more easily.
Descriptive labels help users identify specific components within the content. Labels and headings do not need to be lengthy. A word, or even a single character, may suffice if it provides an appropriate cue to finding and navigating content.
It is important to help a person know which element among multiple elements on the page has the keyboard focus. Note that a keyboard focus indicator can take different forms. One common way is a caret within the text field to indicate that the text field has the keyboard focus. Another is a visual change to a button to indicate that the button has the keyboard focus.

2.5 Input Modalities

The intent of WCAG 2.5 Input Modalities Success Criterion is to ensure that content can be controlled with a range of pointing devices, abilities, and assistive technologies.

Some people cannot perform gestures in a precise manner, or they may use a specialized or adapted input device such as a head pointer, eye-gaze system, or speech-controlled mouse emulator. Some pointing methods lack the capability or accuracy to perform multipoint or path-based gestures. Make it easier for users to prevent accidental or erroneous pointer input. People with various disabilities can inadvertently initiate touch or mouse events with unwanted results.
The intent of this Success Criterion is to ensure that the words which visually label a component are also the words associated with the component programmatically. This helps ensure that people with disabilities can rely on visible labels as a means to interact with the components. Most controls are accompanied by a visible text label. Those same controls have a programmatic name, also known as the Accessible Name. Users typically have a much better experience if the words and characters in the visible label of a control match the accessible name. When these match, speech-input users (using speech recognition applications) can navigate by speaking the visible text labels of components, such as menus, links, and buttons, that appear on the screen. Mismatches between visible labels and programmatic names for controls are even more of an issue for speech-input and text-to-speech users who also have cognitive challenges. Mismatches create an extra cognitive load for speech-input users, who must remember to say a speech command that is different from the visible label they see on a control. It also creates extra cognitive load for a text-to-speech user to absorb and understand speech output that does not match the visible label.

WCAG3: Understandable Success Criteria

Information and the operation of user interface must be understandable. This means that users must be able to understand the information as well as the operation of the user interface. Page Titles must be unique and meaningful. Links and Buttons must have concise and clearly marked text labels. The web page must have clearly defined user instructions, and a separation of information content.

3.1 Readable

The intent of WCAG 3.1 Readable Success Criteria is to define the language of the page. This will ensure that content developers provide information in the web page that user agents need to present text and other linguistic content correctly.

Both assistive technologies and web browsers can render text more accurately when the language of the web page is identified.
Screen readers can load the correct pronunciation rules.
Visual browsers can display characters and scripts correctly.
Media players can show captions correctly.
As a result, users with disabilities will be better able to understand the content.
Be shure to include a definition for words used in an unusual way or as an abbreviation (such as a link to a glossary or within the text context).
Often words or characters have different meanings, each with its own pronunciation. The meaning of such words or characters can usually be determined from the context of the sentence. When the sentence is read aloud and the screen reader reads the word using the wrong pronunciation, it can be even more difficult to understand than when read visually.
When words are ambiguous or indeterminate unless the pronunciation is known, then providing some means of determining the pronunciation is needed.

3.2 Predictable

The intent of WCAG 3.2 success criteria is to make web pages appear and operate in predictable ways.

Ensure that functionality is predictable as visitors navigate their way through a document.
Any component that is able to trigger an event when it receives focus must not change the context automatically (such as an automatically submitted form or automatically launching a new window, when a component receives focus).
Changes in context can confuse users who do not easily perceive the change or are easily distracted by changes. Changes of context are appropriate only when it is clear that such a change will happen in response to the user's action.
So, clicking on links or tabs in a tab control is activating the control, not changing the setting of that control.
It is important to design web pages with consistent presentation and layout for users who interact with repeated content within a set of web pages and need to locate specific information or functionality more than once.
Individuals with low vision who use screen magnification to display a small portion of the screen at a time often use visual cues and page boundaries to quickly locate repeated content.

3.3 Input Assistance

The intent of WCAG 3.3 Input Assistance Success Criteria is to ensure that users are aware that an error has occurred and can determine what is wrong.

The error message should be as specific as possible. In the case of an unsuccessful form submission, re-displaying the form and indicating the fields in error is insufficient for some users to perceive that an error has occurred.
Screen reader users will not know there was an error until they encounter one of the indicators. They may abandon the form altogether before encountering the error indicator, thinking that the page simply is not functional.
When possible ensure that users receive appropriate suggestions for correction of an input error. Content authors must present instructions or labels that identify the controls in a form so that users know what input data is expected.
Users with disabilities may be more likely to make mistakes.
People with reading disabilities may transpose numbers and letters, and those with motor disabilities may hit keys by mistake.
Providing the ability to review and correct information gives the user an opportunity to detect a mistake before taking an action that has serious consequences.
Help users avoid making mistakes by Using context-sensitive help, users can find out how to perform an operation without losing track of what they are doing.

WCAG4: Robustable Success Criteria

Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, like browsers and assistive technologies.
This means that users must be able to access the content as technologies advance. Meeting this requirement helps maximize compatibility with current and future user agents, like screen readers. In particular, it enables assistive technologies to process the content reliably, and to present or to operate it in different ways.
This includes non-standard buttons, input fields, and other controls. To deliver a desirable user experience, there must be a separation between web page design and user content. The web page may not render as expected in all browsers, and will not perform as expected in differing screen readers.

4.1 Compatible

The intent of this Success Criterion is to ensure that user agents, including assistive technologies, can accurately interpret and parse content.

If the content cannot be parsed into a data structure, then different user agents may present it differently or be completely unable to parse it.
Some user agents use "repair techniques" to render poorly coded content.
Note: This criterion has been removed from WCAG 2.2.
In WCAG 2.1 and 2.0 this Success Criterion should be considered as always satisfied for any content using HTML or XML.

WCAG5: Conformance Success Criteria

Conformance to a standard means that you have satisfied the requirements of the standard. To conform to the WCAG standard, you need to satisfy the Success Criteria. In order to accommodate different situations that may require or allow greater levels of accessibility than others, WCAG has three levels of conformance: A, AA, AAA.

5.1 Conformance Level

The first requirement deals with the levels of conformance. It basically says that all information on a page conforms or has a conforming alternate version that is available from the page. One of the three levels of conformance (A, AA or AAA) must be met in full.

5.2 Full Pages

The WCAG 5.2 Full Pages Success Criteria provision simply requires that the whole page conform. That is, statements about part of a page conforming cannot be made.
For example, a long description of a graphic might be on a separate page that the user can jump to, or an alternative can also be provided on the same page.

5.3 Complete Processes

WCAG 5.3 Complete Processes Success Criteria is concerned with multiple web pages that are needed to complete a task.
When a web page is one of a series of web pages presenting a process, such as a sequence of steps that need to be completed in order to accomplish an activity, all web pages in the process must conform at the specified level or better.
This would prevent a shopping site from being classified as conforming if the checkout, or some other feature, of the web site shopping process do not conform.

5.4 Only Accessibility-Supported Ways of Using Technologies

The WCAG 5.4 success criteria requires that only accessibility-supported ways of using technologies are relied upon to satisfy the success criteria.
Many of the Success Criteria deal with providing accessibility through assistive technologies, or special accessibility features in mainstream user agents; For example, a show captions option in a media player. That is, the Success Criteria require that something be done in the web content that would make it possible for assistive technologies to successfully present the content's information to the user.
So, a picture that you were supposed to click on to go to a topic would not be accessible to a person who was blind, unless text alternatives describing the picture and the picture is defined as a Button, were provided in a way that user agents including assistive technologies can find and display them.

5.5 Non-Interference

The WCAG 5.5 Non-Interference Success Criteria requires that if technologies are used in a way that is not accessibility supported, then they must not block the ability of users to access the rest of the page.
This means that technologies that are not accessibility supported can be used, as long as all the information is also available using technologies that are accessibility supported, and as long as the non-accessibility-supported material does not interfere.