Æ (lower case: æ) is a grapheme formed from the letters a and e. Originally a ligature representing a Latin diphthong, it has been promoted to the full status of a letter in the alphabets of some languages, including Danish, Faroese, Norwegian and Icelandic. As a letter of the Old English Latin alphabet, it was called æsc ("ash tree") after the Anglo-Saxon futhorc rune ᚫ (), which it transliterated; its traditional name in English is still ash /æʃ/.
In English, usage of the ligature varies in different places. In modern typography, and where technological limitations make its use difficult (such as in use of typewriters), æ is often eschewed in favour of the digraph ae. This is often considered incorrect especially when rendering foreign words where æ is considered a letter (e.g. Æsir, Ærø) or brand names which make use of the ligature (e.g. Æon Flux, Encyclopædia Britannica). In the United States, the problem of the ligature is sidestepped in many cases by use of a simplified spelling with "e"; compare the common usage, medieval, with the traditional mediæval. However, given the long history of such spellings, they are sometimes used to invoke archaism or in literal quotations of historic sources; for instance, words such as dæmon are often treated in this way. Often, it will be replaced with the digraph as in archaeology. It is seen on gravestones of the 19th century, in place of "age" (at the time of death), i.e. "Æ xxYs, yyMs, zzDs."