In Latin, a stemless variant shape of the upsilon was borrowed in early times as U, taking the form of modern-day V – either directly from the Western Greek alphabet or from the Etruscan alphabet as an intermediary – to represent the same /u/ sound, as well as the consonantal /w/, num – originally spelled NVM – was pronounced /num/ and via was pronounced [ˈwia].

From the 1st century AD on, depending on Vulgar Latin dialect, consonantal /w/ developed into /β/ (kept in Spanish), then later to /v/.

Printers eschewed capital ⟨U⟩ in favor of ⟨V⟩ into the 17th century and the distinction between the two letters was not fully accepted by the French Academy until 1762.

[4][5][better source needed] The rounded variant became the modern-day version of U and its former pointed form became V. In English, the letter ⟨u⟩ has four main pronunciations.

Short ⟨u⟩, found originally in closed syllables, most commonly represents /ʌ/ (as in 'duck'), though it retains its old pronunciation /ʊ/ after labial consonants in some words (as in 'put') and occasionally elsewhere (as in 'sugar').

Additionally, the letter ⟨u⟩ is used in text messaging, the Internet, and other written slang to denote 'you', by virtue of both being pronounced /juː/.