During the late Middle Ages, two forms of "v" developed, which were both used for its ancestor u and modern v. The pointed form "v" was written at the beginning of a word, while a rounded form "u" was used in the middle or end, regardless of sound. So whereas valor and excuse appeared as in modern printing, "have" and "upon" were printed haue and vpon. The first distinction between the letters "u" and "v" is recorded in a Gothic alphabet from 1386, where "v" preceded "u". By the mid-16th century, the "v" form was used to represent the consonant and "u" the vowel sound, giving us the modern letter "u". Capital "U" was not accepted as a distinct letter until many years later.
In English there is also a "short U", which in most dialects of English is an open-mid back unrounded vowel [ʌ].
U is used to mark enzyme unit .
The EBCDIC code for capital U is 228 and for lowercase u is 164.
Letter U with diacritics
|Letter-digit and digit-letter combinations|