U is a letter of the Cyrillic script. It commonly represents the close back rounded vowel, somewhat like the pronunciation of ⟨oo⟩ in "boot" or "rule". The forms of the Cyrillic letter U are similar to the lowercase of the Latin letter Y, with the lowercase Cyrillic letter U's form being identical to that of small Latin letter Y.

The Cyrillic script, Slavonic script or simply Slavic script is a writing system used for various languages across Eurasia. It is the designated national script in various Slavic, Turkic, Mongolic, Uralic, Caucasian and Iranic-speaking countries in Southeastern Europe, Eastern Europe, the Caucasus, Central Asia, North Asia, and East Asia, and used by many other minority languages.