People with a variety of print disabilities (including low vision, dyslexia, other cognitive disabilities) can benefit from being able to increase the spacing between lines, words, and/or letters on their own device.
Paragraphs of text are a fundamental core of web content. It's important to display them in a fashion that is optimally readable to the majority of your audience.
A clear indication that specific form fields are required can save users time and avoid potential errors relating to missing data when a form is submitted.
For a number of reasons including data persistence, performance and security, it is sometimes beneficial to terminate idle user sessions. It's important to warn people a session is about to expire and give them the option to continue.
Users can find their way around a web site more easily and confidently if they know where they are.
The heading levels (1-6) are often considered a way of describing and determining the “importance” of a heading, with h1 being the most important.
For a readable interface, it's important to use visual cues to group or separate content to show which content relates to other content.
When positioning elements using CSS, it's possible to place them in a position that does not reflect their location in the source order. This can have unexpected side effects for keyboard-navigation users.
Icon fonts are a popular and effective method for providing scalable symbols that can be used to label controls and provide graphical information. The information provided by icons also needs to be available to people who can’t see them.