This is not an exhaustive list of digital accessibility guidelines or standards. This list represents common concepts found throughout the guide and is intended to give some foundational information for those who are new to digital accessibility and accessibility testing. It can also be used as a selected resources list, capturing a few testing tools and resources for each core concept.
Alternative Text (Alt Text)
Images that convey meaningful visual information need alternative text to describe that information. Alt text should provide the same information that the image is meant to convey, not just a description of the image with details that aren’t relevant or are already included in other text.
Further reading:
- An alt Decision Tree
A decision tree which helps you determine if alt text is needed. Focused on web content but the concepts are relevant to all alt text. - Authoring Meaningful Alternative Text | Section508.gov
An article with information about the purpose of alt text, general guidance, and guidance for a variety of specific types of images. - WebAIM: Alternative Text
An article which describes the purpose of alternative text and how to write context appropriate alternative text.
The method of checking for alt text varies between types of documents/content. Specific tools and guidance can be found within each content type in this guide.
Color Contrast or Contrast Ratio
A measure of the difference in perceived brightness between two colors.
Further reading:
- Contrast and Color Accessibility
Information from WebAIM about WCAG 2 contrast and color requirements. - WCAG 2 “Contrast Ratio”
More details from WebAIM about WCAG 2’s “contrast ratio.”
Testing tools:
- AccessibleWEB Color Contrast Checker
A Google Chrome Extension that displays color contrast ratios and displays WCAG conformance results. - Chrome High Contrast extension
High Contrast lets you browse the web with your choice of several high-contrast color filters designed to make it easier to read text. - Colour Contrast Analyser
Easy to use application, available to download for Windows and Mac. Check foreground & background color combinations using an eyedropper tool from anywhere on the screen, including non-web based applications. - WCAG Contrast Checker for Firefox
Firefox extension displays color contrast ratios in a sidebar, and flags the color combinations that fail WCAG contrast requirements. - WebAIM Color Contrast Checker
Online tool includes a feature to “lighten” or “darken” existing colors until you find a combination that meets WCAG 2.1 requirements.
Links
Link text should convey clear and accurate information about the destination.
- For example, instead of reading “click here,” the link text should include the title of the destination page or a description of the destination page.
- Link text should make sense outside the context of the surrounding text.
- Color should not be the only indicator that text is a link. The color of a link should also have sufficient contrast with the background and surrounding text.
Further Reading:
- Accessibility Bytes No. 4: Descriptive Links and Hypertext
A short article with key principles for accessible links and suggestions about testing links. - WebAIM: Links and Hypertext
Most relevant to web content, gives good context about how screen readers interact with links.
Testing Tools:
- Color-reliant Link Contrast Checker
A color contrast checker which compares the link color, background, and surrounding text color.
Lists
The use of formatted lists allows assistive technology to accurately translate the information as lists when reading or displaying the content in modified formats.
- Use built-in unordered (symbols) or ordered (numbered) lists. Simply adding a dash or a number before text may indicate a list item to a visual user but it will not translate to screen-reader users or other assistive technology.
- Ordered (numbered) lists should be used in situations where the order of the list items is important. For example, an ordered list is helpful if you are giving instructions and the order of them is important.
Readability
Plain Language
It is important that written content is readable for the audience it is intended for. Writing clearly and simply is challenging and depends on the context of the content you are creating or testing.
Further Reading:
- WebAIM: Writing Clearly and Simply
An article with guidelines and examples of how to write clearly and simply. - Plain Language Guidelines
Guidelines for the federal Plain Writing Act of 2010. A useful guide for simplifying language.
Testing Tools:
- Hemingway App
An editor which assigns a readability score based on which grade level could understand your writing. The lower the grade level score, the more readable your document is. Hemingway identifies sentences which are hard to read and other common writing issues. The online version is free. There are paid versions with and without generative AI available as well. - Ginger Software and Grammarly
AI-powered grammar, spell checker, and writing assistants with options for Microsoft Word add-ins, browser extensions, and mobile and desktop apps. Both free and paid accounts are available.
Font Size and Style
Font size and style impact people’s ability to see and understand written content. In most cases, there isn’t one correct typeface, spacing, or font size that makes written content accessible to everyone, but considerations to make when creating or testing written content.
Further Reading:
- WebAIM: Typefaces and Fonts
An article with considerations and guidelines around the readability of typefaces and fonts.
Reading Order or Logical Reader Order
Reading order describes the movement through digital content, which should follow an order that matches the visual and logical order of the content. Logical reading order is essential for screen reader users and navigation of the content.
Further Reading:
- Tab and read order in documents
Techniques for setting tab and read order in HTML, PDF documents, and PDF forms, from the University of Washington’s Accessible Technology. - Understanding SC 1.3.2: Meaningful Sequence (Level A)
Information from the World Wide Web Consortium about the success criterion for meaningful reading sequence.
Testing for reading order:
- In most contexts, you can check the reading order and ability to navigate without a mouse by navigating through content and tasks by keyboard alone.
- Try the #NoMouse Challenge
More techniques to test for reading order varies between types of documents/content. Specific tools and guidance can be found within each content type in this guide.
Headings
- In documents and webpages, headings impact reading order.
- Testing for headings often requires some manual checking.
- Best practices for headings include:
- Headings should follow a logical hierarchy, starting with the main topic (H1) and then using subheadings (H2, H3, etc.) to organize content into sections and subsections.
- Avoid skipping heading levels. For example, don’t go from an H1 to an H3 without an H2 in between.
- Each page should have only a single Heading 1, which represents the page or document title.
- Headings should be descriptive and accurately reflect the content they introduce.
Further Reading:
- WebAIM: Headings
A short article focused on web page headings. Useful reading for context in documents as well.
Screen Readers / Text-to-Speech
Screen Readers and Text-to-Speech software can be useful when testing content for accessibility by giving you insight into the experience of a user trying to access your content with that software. They are most helpful for testing the navigation and structure of content.
Screen Readers
Screen readers are comprehensive tools that interpret and read screen text and other screen elements aloud. They require some specialist knowledge and can be challenging for beginners to use. This list includes a few common screen readers and is not comprehensive.
- JAWS
Jaws has been one of the most popular screen readers for many years, Jaws is not free, but anyone with a (dot) EDU email qualifies for the student annual licence pricing. Requires specialist knowledge.- WebAIM guide on Using JAWS to Evaluate Web Accessibility
- Narrator
Microsoft’s screen reader, which ships with Microsoft Windows. Requires specialist knowledge.- WebAIM guide on Using Narrator to Evaluate Web Accessibility
- NVDA Screen Reader
The NonVisual Desktop Access (NVDA) screen reader can be downloaded free of charge by anyone. Requires specialist knowledge.- Quick Reference Guide for Windows from Deque (PDF)
- WebAIM guide on Using NVDA to Evaluate Web Accessibility
- VoiceOver
Apple’s screen reader, which ships with Mac OS and iOS devices such as the iPhone and iPad. Requires specialist knowledge.- WebAIM guide on Using VoiceOver to Evaluate Web Accessibility.
Text-to-Speech Tools
Text-to-speech (TTS) tools are generally less robust than screen readers. They focus on converting written text into spoken words. Developers may build them into apps or databases, or users may add them using options such as browser extensions.
- Read Aloud is a text-to-speech browser extension available for Chrome, Edge, and Firefox browsers.
- ReadSpeaker is a built-in text-to-speech tool found in many databases, including EBSCO, Gale, and ProQuest platforms. The visibility for this tool is usually an administrator setting.
- Microsoft products have a few built-in text-to-speech options.
- Speak is a text-to-speech feature available in Word, Outlook, PowerPoint, and OneNote, which can be added to your quick access toolbar.
- Speak only reads aloud the text you have highlighted and is only available on Windows devices (a similar feature, called Speech, is available for MacOS).
- Further reading: Use the Speak text-to-speech feature to read text aloud – Microsoft Support
- Read Aloud (a different tool than the one above) is available by default in Word (in the Review Menu) and Outlook (in the Home toolbar, under More Commands).
- Further reading: Listen to your Outlook email messages – Microsoft Support
- Immersive Reader is a tool similar to a screen reader with more functionality than the other Microsoft read aloud features. Immersive Reader can also be used in Microsoft Edge, allowing you to use it on web pages.
- Speak is a text-to-speech feature available in Word, Outlook, PowerPoint, and OneNote, which can be added to your quick access toolbar.
Tables
It is recommended to avoid tables in certain content types, especially tables used for layout or formatting rather than to organize data. In cases where data tables are needed, proper row and column headers are essential.
Further reading:
- WebAIM: Creating AccessibleTables
A brief article which discusses the difference between layout tables and data tables, the issues tables cause for screen reader users, and some guidelines for creating tables.
Techniques for testing tables vary between content types. Specific guidance can be found within each content type in this guide.
Navigating to Other Content Types
Use these links to continue (or return) to the other content types in this section: