"Ä", or "ä", is a glyph which represents either a letter from several extended Latin alphabets, the letter A with umlaut, or a letter A with diaeresis.
Letter Ä
The letter Ä occurs in the Finnish, Swedish, Estonian, and Slovak alphabets, where it represents a vowel sound. In Finnish this is always ; in Swedish and Estonian regional variation allows for either [æ] and [ɛ], as for example in some common Swedish dialects by här [hæ:r] and väg [vɛ:g].
In the Slovak language Ä stands for [ɛ] (or a bit archaic but still correct [æ]). The diacritical sign is called dve bodky ("two dots"), and the full name of the letter "ä" is a s dvomi bodkami ("a with two dots").
A-umlaut
A similar glyph, A with umlaut, appears in the German alphabet. It represents the umlauted form of a, resulting in [ɛ]. The letter is collated together with A. The letter also occurs in some languages which have adopted German names or spellings, but is not a part of these languages' alphabets.
In other languages that do not have the letter as part of the regular alphabet or in limited character sets such as ASCII, A-umlaut is frequently replaced with the two-letter combination "ae".
In the Icelandic, Danish and Norwegian alphabets, A-umlaut is often replaced with its equivalent "Æ".
A-diaeresis
A with diaeresis occurs in several languages which use diaereses. In these languages the letter represents a normal A, and the pronunciation does not change.
Typography
Historically A-diaeresis was written as an A with two dots above the letter. A-umlaut was written as an A with a small e written above: this minute e degenerated to two vertical bars in medieval handwritings. In most later handwritings these bars in turn nearly became dots. The origin of the letter Ä was a similar ligature for the digraph "AE": e was written above a and degenerated into two small dots.
Æ, a highly similar ligature evolving from the same origin as Ä, evolved in the Icelandic, Danish and Norwegian alphabets. The Æ ligature was also common in Old English, but had largely disappeared in Middle English.
In modern typography there was insufficient space on typewriters and later computer keyboards to allow for both an A-with-dots (also representing Ä) and an A-with-bars. Since they looked near-identical the two glyphs were combined, which was also done in computer character encodings such as ISO 8859-1. As a result there was no way to differentiate between the different characters. While Unicode theoretically provides a solution, this is almost never used.
Ä is also used to represent the ə (the schwa sign) in situations where the glyph is unavailable, as used in the Turkmen, Tatar , and Azeri languages.
The HTML entity for Ä is Ä. For ä, it is ä (Mnemonic for "A umlaut").
