Readability and legibility are key considerations for all users. For people with disabilities, these attributes can be essential to a successful user experience. For example, some people may have difficultly tracking along a line of text if its line height (a.k.a. leading) is too wide or too narrow. Some people need to enlarge text to read it and will not be able to access content set in a text size that is small or doesn't scale correctly.
For optimal readability:
- Use visual and semantic space. Space is an important visual design tool that helps us identify groups of related content and delineate unrelated content. Non-visual users benefit from "space" that is created using semantic markup (see Solid Structure).
- Provide the right amount of space between lines of text. For most content work, the interline spacing (line-height) is applied automatically.
- Use clean typography. Avoid changing the typeface from that specified by the website.
- Avoid using all caps. Readability is reduced with all caps because all words have a uniform rectangular shape, meaning readers can't identify words by their shape.
- Don’t underline text. Reserve underlining for identifying links.
- Use left-aligned text. A consistent left margin makes reading easier.
- Don’t put two spaces after a period. Period.
- Support text resizing. Check how your content responds to enlarged text. Avoid using narrow columns of content because they will not respond well to scaling.
- Ensure your content is coded using semantic markup (see Testing section under Identify headings, lists, and tables).
- Scan the “color” of your page. Is there an even color, with only important elements drawing attention, like headings?
- Enlarge your text size in the browser. Does the text resize? Does the layout stay intact, or do elements overlap and clip?