Underline text generator

A combining mark has no width of its own. It's drawn on, over or under the character just before it, the same way é can be stored as an e followed by an accent mark. So “Read this first” in the underline style is 13 ordinary letters with 13 marks tucked in after them. Nothing about the letters themselves changes.

That makes these styles different from bold or cursive, which replace each letter with a maths character. Here the R is still an R. It's also why they work on any character: accented letters like é, Cyrillic or Greek letters, numbers and punctuation all take a mark.

The generator puts no mark on spaces or line breaks, so the underline stops at the end of each word and starts again at the next. Each word gets its own line.

Inside a word, what you see depends on the font. Every mark is drawn separately under its own letter, so if the font doesn't stretch the mark to fit, wide letters like m and W get a line that falls short, leaving small gaps that make the underline look dashed. In some fonts the line also runs through the tails of g, j, p, q and y. Two phones can show the same underlined word differently, and neither is wrong.

Tip: For the most solid-looking line, underline a short word in capitals. Most capitals have no tails for the line to run through.

Underlining is a habit from typewriters. They had one typeface and no bold or italics, so typists marked titles and emphasis by backspacing over a word and typing underscores beneath it. That is why older style guides tell you to underline book titles that print would set in italics.

Editors kept the code. In traditional proofreading marks, one straight line under a word tells the printer to set it in italics, two lines mean small capitals, three mean full capitals and a wavy line means bold. Accountants have a convention of their own: a double line under a figure marks a final total.

The other two styles come from maths and phonetics. A line over digits, called a vinculum, marks a repeating decimal, so 0.3̅ means 0.333… for ever. Two dots below a letter are the International Phonetic Alphabet's mark for breathy voice, the murmured quality some languages give to certain consonants and vowels.

On the web, underlined text has meant “tap here” for decades, so readers may try to tap an underlined word and wonder why nothing opens. Use underline for a heading or one word you want noticed, and keep it away from real links so the two aren't confused.

For screen readers, underline is the gentlest of the Unicode tricks, because the letters underneath are ordinary. Results still vary: some read the word normally, some pause on or announce each mark, and some spell the word out. If an underlined heading carries important information, repeat it in plain words.