Verbs can be transitive (перехідні́) or intransitive (неперехідні́), depending on whether or not they require an object to express a complete thought. Most verbs are transitive. They direct their action towards the object.

Examples with transitive verbs:

Я чита́ю кни́гу. - I read a book.
Я відкрива́ю раху́нок. - I open an account.
Я вивча́ю украї́нську. - I am learning Ukrainian.
Я ми́ю мою́ тарі́лку. - I am washing my plate.

The following verbs belong to intransitive group:

1. Reflexive verbs, the verbs ending in "-ся", "-сь": усміхатися (to smile), умиватися (some verbs can come from transitive form "умивати - умиватися" - to wash);
2. impersonal verbs denoting the state of nature or man: дощить (it rains);
3. verbs with the meaning of moving in space: іти (to go), летіти (to fly), бігти (to run), etc.

Examples with intransitive verbs:
Він сміє́ться. - He is laughing.
Вона́ посміха́ється. - She is smiling.
Вони́ біжа́ть. - They run.
Йде сніг. - It snows.
Вони́ готу́ються до екза́мену. - They are preparing for the test.

Most of intransitive verbs end with the particle "-ся", "-сь". If a verbs requires a preposition to connect with a noun in accusative case it is an intransitive verb.

Сіда́ти в маши́ну. - To get in the car. (Lit. to sit in the car)

Note: Sentences with an intransitive verb cannot be changed into passive voice.

There are a few verbs which can be transitive and sometimes intransitive depending on a situation.

Він малю́є карти́ну. - He paints a picture. (transitive)
Він га́рно малю́є. - He paints well. (intransitive)