11-2 Accessibility Standards Explained
Key Concepts
- Web Content Accessibility Guidelines (WCAG)
- Section 508
- Accessible Rich Internet Applications (ARIA)
- Color Contrast
- Keyboard Navigation
- Screen Reader Compatibility
- Alt Text for Images
- Semantic HTML
- Accessible Forms
- Audio and Video Accessibility
- Mobile Accessibility
Web Content Accessibility Guidelines (WCAG)
WCAG is a set of guidelines developed by the World Wide Web Consortium (W3C) to make web content more accessible to people with disabilities. These guidelines are organized into four principles: perceivable, operable, understandable, and robust.
Example: Ensuring that text alternatives are provided for non-text content, such as images, to make it accessible to screen readers.
Section 508
Section 508 is a U.S. federal law that requires electronic and information technology developed, procured, maintained, or used by the federal government to be accessible to people with disabilities. It includes guidelines for web accessibility.
Example: A government website must ensure that all multimedia presentations have synchronized captions to comply with Section 508.
Accessible Rich Internet Applications (ARIA)
ARIA is a set of attributes that can be added to HTML elements to make dynamic content and advanced user interface controls accessible. It provides additional information to assistive technologies.
Example: Using ARIA roles like "button" and "alert" to describe the purpose of interactive elements to screen readers.
Color Contrast
Color contrast refers to the difference in luminance between text and its background. High contrast ensures that text is readable for users with low vision or color blindness.
Example: Ensuring that the contrast ratio between text and background is at least 4.5:1 for normal text and 3:1 for large text, as recommended by WCAG.
Keyboard Navigation
Keyboard navigation ensures that all interactive elements on a webpage can be accessed and operated using a keyboard, without requiring a mouse. This is essential for users who rely on keyboard input.
Example: Ensuring that users can tab through all links, buttons, and form fields on a webpage in a logical order.
Screen Reader Compatibility
Screen reader compatibility involves designing web content that can be effectively read and navigated by screen readers, which are tools used by visually impaired users to access information on the web.
Example: Using semantic HTML elements like headers (h1, h2) and lists (ul, ol) to structure content in a way that is easily navigable by screen readers.
Alt Text for Images
Alt text (alternative text) is a text description of an image that is read by screen readers. It provides context and information about the image for users who cannot see it.
Example: Adding alt text to an image of a company logo that describes the logo and its purpose on the webpage.
Semantic HTML
Semantic HTML involves using HTML elements that convey the meaning of the content to both the browser and the developer. This helps assistive technologies understand the structure and context of the content.
Example: Using the "nav" element to define a navigation section, which helps screen readers identify and navigate the site's main menu.
Accessible Forms
Accessible forms ensure that all form elements are labeled and can be easily navigated and understood by users with disabilities. This includes using proper labels, instructions, and error messages.
Example: Associating a label with each form input using the "for" attribute, so screen readers can accurately describe the input fields.
Audio and Video Accessibility
Audio and video accessibility involves providing alternatives for multimedia content, such as captions, transcripts, and audio descriptions, to make them accessible to users with hearing or visual impairments.
Example: Adding captions to a video tutorial so that deaf or hard-of-hearing users can follow along.
Mobile Accessibility
Mobile accessibility ensures that web content is accessible on mobile devices, including smartphones and tablets. This involves designing for touch interactions, responsive layouts, and ensuring content is readable on smaller screens.
Example: Designing a mobile-friendly menu that can be easily expanded and collapsed using touch gestures.