1. In computer science, a U is the height of the chassis, that is, 44 mm or 1.75 inches.

2. In IT technology, U is the unit representing the external size of the server, which is the abbreviation of unit. Detailed dimensions are determined by the American Electronics Industry Association (EIA) as an industry group. 1U = 4.445 cm.

3. In physics, the symbol representing electric potential or voltage is V (Volt for short).

4. Mathematically, ∪ stands for union and ∩ inverted ∩ stands for intersection (both an operation symbol and a set).

5. "u" homophones "you". For example, "I love you", "You start" and so on.

6. U also refers to the anime "Naruto", which has the skull of Naichi Bo, a talented ninja of the Naichi Bo family in Saringen. Many Naruto fans use the abbreviation U.