"Umlaut" (m.), noun
The German alphabet consists of 26 characters plus 3 umlauts: ä, ö and ü.
The two dots above the letters do NOT indicate an accentuation or emphasis of the syllable (as for instance accent-bearing letters in Spanish or French). Umlauts are used as independent characters in the German language.
Whenever the use of umlauts is not possible (e.g. for technical reasons, in email addresses or names of websites), umlauts are indicated by the following combinations:
“ae” = ä, “oe”= ö, “ue” = ü.
some proper names contain the converted form of umlauts
(e.g. the author is spelled Goethe
The letter ä is pronounced like the a in “apple”.
The sound of the letter ö is similar to the sound in “earn” or “bird”.
The letter ü is the most difficult for those who are learning German. It is the same sound as the u in the French words “musique”, “chaussure”, “rue”, ... etc.
Umlauts are used in all types of word categories: nouns (not only, but often in the plural form), verbs, adjectives, adverbs, prefixes and prepositions.
Ä: Äpfel, Hände, wärmen
Ö: Löwe, Köln, mögen,
Ü: Küsse, Frühling, wünschen