diacriticals

Diacritical marks, or diacritics, are signs added to letters to change their pronunciation or distinguish otherwise identical words. They include the acute (é), grave (è), and circumflex (â); the tilde (ã, õ) and the diaeresis/umlaut (ë, ö, ü); the cedilla (ç); the caron/hacek (č, š); the ring above (å); and many others such as the ogonek (ą) and the macron (ā). Diacritics affect vowel quality, stress, tone, nasalization, and consonant modification, and they are integral to the orthographies of many languages.

In use, diacritics can indicate pronunciation as in French and Spanish, where accents mark vowel quality or stress and distinguish otherwise identical words. In German, the umlaut changes a vowel's timbre and can create a distinct letter (ä, ö, ü). In Polish and Czech, háček or ogonek modify consonants and vowels to create new phonemes. Some languages also rely on diacritics for tone (as in Vietnamese) or to distinguish minimal pairs in loanwords.

In writing and digital text, diacritics are encoded as single characters or as base letters with combining marks. Unicode supports both precomposed characters and combining diacritical marks; normalization (NFC, NFD) affects matching and rendering. Input methods include composing keys or dead keys and on-screen keyboards; font coverage and rendering quality influence legibility and accuracy.

Historically, the term diacritic comes from Greek diakritikos, meaning distinguishing or differentiating. Diacritics remain essential for accurate spelling, meaning, and pronunciation in many languages.