Ü — the letter U with umlaut or diaeresis

Characteristics and pronunciation

Phonetically, Ü typically corresponds to a close front rounded vowel ([y]) when long and a near-close front rounded vowel ([ʏ]) when short. Languages vary in whether this is a separate letter or a modified form of U. In German the two dots are called an umlaut and mark a sound change related to historical fronting; in languages such as Spanish the same two-dot mark is called a diaeresis and serves a different orthographic purpose. See the distinction and examples in the sections below and in language-specific references like German usage and Turkish usage.

History and typographic origin

The diacritic developed in medieval scribal practice. Scribes wrote a small superscript e above vowels to indicate a following front vowel or secondary articulation; over time that tiny e simplified into two short strokes and then into two dots. This evolution explains why German speakers call the mark an Umlaut (literally "around-sound") while typographers distinguish the visual two-dot diacritic from the separate mark used for diaeresis in Romance languages.

Orthography and examples

• German: Ü is found in words like über and München. When the diacritic is unavailable, ue is commonly used as a substitute (for example Mueller for Müller) — see orthographic notes.
• Turkic languages: Turkish and Azerbaijani treat Ü as a distinct letter of the alphabet and sort it separately; examples include Turkish gül ("rose"). See general Turkic usage at Turkic languages.
• Other languages: Hungarian and Estonian include ü as a separate vowel; Spanish uses the diaeresis ü rarely to indicate that a normally silent u is pronounced (as in vergüenza), not to mark [y].

Writing, encoding and notable facts

In digital text Ü and ü are encoded in Unicode and are widely supported across fonts and keyboards. When a keyboard does not offer the character, users often substitute letter pairs (such as ue in German) or apply input methods that produce the diacritic. The distinction between umlaut (a phonological change or diacritic in Germanic languages) and diaeresis (a pronunciation marker in Romance orthographies) is a common source of confusion; the same glyph can serve different linguistic functions in different traditions. For further reading see language-specific pages like usage overview and Turkish alphabet.

Summary

Ü/ü is more than a typographic variant of U: in many alphabets it represents a separate vowel with fronted lip-rounding, and in some writing systems it simply signals pronunciation. Its origins as a small superposed e explain the two-dot form, and its treatment varies by language, orthography and historical development.