The Dative Plural of Nouns

Дательный падеж имён существительных (мн.ч.)

1) The dative case of a noun denotes the person or object to whom or which the action is addressed

and answers the questions кому? (to whom?), чему? (to what?)

Я помогаю друзьям.

2) The dative with the preposition к is used to indicate the person who is the aim of the motion

or an object or a place to which the motion is directed.

The dative answers the questions к кому? (to whom?), к чему? (to what?)

К кому ты идёшь? - Я иду к товарищам.

3) When asking or saying a person's or object’s age, the person or the object should be in the dative case

and answers the questions кому? (to whom?), чему? (to what?)

Сколько лет этим городам? - Больше тысячи лет.

4) The dative is used in impersonal constructions to denote the person who performs an action or experiences some state.

In impersonal constructions the dative is used with the words надо (must, it is necessary), нужно (must, it is necessary),

можно (may), нельзя (must not) followed by an infinitive.

Детям нельзя курить.