у

very common #16A1

preposition

1.
to have, (indicating possession)
У неё есть маши́на.
She has a car.
у + noun/pronoun in the genitive, usually with есть: у меня есть...
2.
by, at, next to
Забронируй ме́сто у окна́!
Book a window seat!
у + object in the genitive case
3.
with (someone), at (someone's place)
Он до́лго жил у роди́телей дру́га.
He lived at his friend's parents' place for a long time.
у + person in the genitive case, of staying or living at someone's home
4.
from (someone)
Маша взяла́ э́то пла́тье у подру́ги.
Masha borrowed this dress from her friend.
у + person in the genitive case, with verbs like взять, спросить, купить

Usage info

у окна́ - by the window
У Ива́на есть маши́на - Ivan has a car

This last example shows that it is imperative for learners of Russian to know that the construction literally means: 'At/near/on ... Ivan is a car'. Otherwise, people who have just the one verb for 'to have' in their native languages (and express possession in an SVO-manner) can't make head nor tail of this most Russian of ways of expressing possession ('име́ть' admittedly means 'to have', but not usually in the literal sense).

Examples

У ма́льчика хоро́шие рефле́ксы.
The boy has good reflexes.
У короле́й дли́нные руки.
Kings have long arms.
У моего́ сы́на плохо́е здоро́вье.
My son is subject to ill health.
У э́того молока́ стра́нный вкус.
This milk tastes odd.
«Где ты был?» — «У парикма́хера».
Where have you been? "I've been to the barber's."
У исто́рии хоро́ший коне́ц.
The story ends happily.
У ма́льчика высо́кая температу́ра.
The boy has a high fever.
У э́того пиани́но хоро́шее звуча́ние.
The piano has a good tone.

Typical usagePRO

Possession (have / don’t have)
- у меня́ есть вре́мя
  I have time
- у меня́ нет вре́мени
  I don’t have time
- у него́ есть сестра́
  He has a sister
- у неё есть иде́я
  She has an idea
At someone’s place / person
- у меня́ до́ма
  at my place (at home)
- у него́ до́ма
  at his place
- у врача́
  at the doctor’s
- у роди́телей
  at (my/the) parents’ place
By/at a place or object
- у окна́
  by the window
- у двери́
  by the door
- у вхо́да
  at the entrance
- у вы́хода
  at the exit