These articles provides practical advice on how to write your web content so that it conforms to the success criteria outlined in the Perceivable principle of the Web Content Accessibility Guidelines (WCAG) 2.0 and 2.1. Perceivable states that users must be able to perceive it in some way, using one or more of their senses.
Easy to perceive Information and user interface components must be presentable to users in ways they can perceive: A website is perceivable when a user can use their sense(s) of sight, sound, and touch to identify and process the information presented. Under this principle you will find guidelines relating but not limited to: Let’s see…
1.4.1 Use of Color (A): Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. (Level A) Requirements Color alone is not used to convey information (e.g. to identify form fields with invalid entries or the current step in a step indicator)…
1.4.2 Audio Control (A): If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level. (Level A) Requirements Audio content does not start playing automatically,…
1.4.3 Contrast Minimum (AA): The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for the following: (Level AA) Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1; Incidental: Text or images of text that are part of an…
1.4.4 Resize Text (AA): Except for captions and images of text, text can be resized without assistive technology up to 200 percent without loss of content or functionality. (Level AA) Requirements When the whole page, or its text content only, is enlarged, all information and functionality should remain available. Ensure that the content and layout…
1.4.5 Images of text (AA): If the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text except for the following: (Level AA) Customizable: The image of text can be visually customized to the user’s requirements; Essential: A particular presentation of text is essential to the…
1.4.10 Reflow (AA): Content can be presented without loss of information or functionality, and without requiring scrolling in two dimensions for: Vertical scrolling content at a width equivalent to 320 CSS pixels; Horizontal scrolling content at a height equivalent to 256 CSS pixels. Except for parts of the content which require two-dimensional layout for usage…
1.4.11 Non-Text Contrast (AA): The visual presentation of the following have a contrast ratio of at least 3:1 against adjacent color(s): User Interface Components: Visual information required to identify user interface components and states, except for inactive components or where the appearance of the component is determined by the user agent and not modified by…
1.4.12 Text Spacing (AA): In content implemented using markup languages that support the following text style properties, no loss of content or functionality occurs by setting all of the following and by changing no other style property: Line height (line spacing) to at least 1.5 times the font size; Spacing following paragraphs to at least…
1.4.13 Content on Hover or Focus (AA): Where receiving and then removing pointer hover or keyboard focus triggers additional content to become visible and then hidden, the following are true: Dismissible: A mechanism is available to dismiss the additional content without moving pointer hover or keyboard focus, unless the additional content communicates an input error…
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