In a printed document, don’t underline. Ever. It’s ugly and it makes text harder to read. See for yourself—
Underlining is another dreary typewriter habit. Typewriters had no bold or italic styling. So the only way to emphasize text was to back up the carriage and type underscores beneath the text. It was a workaround for shortcomings in typewriter technology.
Neither your word processor nor your web browser suffers from these shortcomings. If you feel the urge to underline, use bold or italic instead. In special situations, like headings, you can also consider all caps, small caps, or changing the point size.
Not convinced? I invite you to find a book, newspaper, or magazine that underlines text. Aside from supermarket tabloids—was that the look you were going for?—you won’t find any.
Another reason underlining looks worse than bold or italic: underlining is mechanically applied by the word processor. Bold and italic styles are specially designed to match the regular style of the font.
“trackchanges” feature of your word processor will underline text added to the document. This is fine. In fact, it’s one more reason not to use underlining for emphasis—so readers don’t confuse text that’s marked as a revision with text that happens to be underlined.
On the web, hyperlinks have traditionally been underlined. But email lost its hyphen, and the internet lost its capitalization. Consistent with those signs of maturity, I think it’s time to move beyond underlined hyperlinks too.
“Ohcome on! Everyone underlines links!” Some who use underlining sparingly, and often not at all: the New York Times, New York magazine, the Washington Post, the Guardian, the Wall Street Journal, the Atlantic, the New Yorker, the Hollywood Reporter, Bloomberg, Google, Politico, Amazon, Apple, Microsoft, GitHub, Yahoo News, and Wikipedia. Even eBay, paragon of ’90s website design, has relented. Are underlined links dead? Maybe not quite. Dying? For sure.
A vocal minority continues to insist—against logic and years of evidence—that these are merely fringe exceptions, and that I belong to a cult devoted to ruining the web by camouflaging all those precious links. Please take this tinfoil hat, with my compliments.