A diacritical mark is a small symbol added to a letter to change how it sounds or to distinguish it from similar letters. Think of them as helpful decorations that tell you exactly how to pronounce a word.

You see diacritical marks all the time in words borrowed from other languages. The accent marks in café and résumé are diacritical marks that show which syllable to stress. The squiggly line over the n in piñata (called a tilde) tells you to pronounce it “peen-YAH-tah” instead of “pin-AH-tah.” The two dots over a vowel in German words like Zürich change how you say that letter.

Different languages use different diacritical marks to create sounds that don't exist in English. French uses several marks, including the circumflex (the little hat in crêpe) and the cedilla (the hook under the c in français). Spanish uses the tilde and accent marks. Without these marks, readers wouldn't know how to say the words correctly.

Even in English, we occasionally use diacritical marks in borrowed words to preserve their original pronunciation. When you see naïve spelled with those two dots (called a diaeresis), they signal that you should pronounce both vowels separately: “nah-EEV” rather than “nave.”