The Zombie: Underlining non-links
Always a Zombie? Yes (except for a very specific case below)
Severity: medium-high
Why is it a zombie: Causes a large user experience issue where users try to click on something that isn’t clickable. That can frustrate visitors and send them running for post-apocalyptic cover.
Cure the Zombie by: Only underline links. Never use underlines on headings or any other non-clickable piece of content. The one exception is when using the <u> element for it’s actual purpose, marking a misspelled word.