를 • (reul)
- indicates the direct object of a verb
Like other Korean particles, 를 (reul) is a postposition. It marks the preceding noun as the direct object of the following verb. 를 (reul) is optional if it can be inferred that the noun is the direct object (as opposed to the subject).
를 (reul) is used only after a word ending in a vowel. If the preceding word ends in a consonant, 을 (eul) is used instead:
- 책 + 을 => 책을 (chaeg + eul => chaeg-eul)
- 사과 + 를 => 사과를 (sagwa + reul => sagwa-reul)
If the noun is the main topic of the sentence and it can be inferred that the noun is the direct object (as opposed to the subject), 는 (neun) is usually used instead.
- (subject marker) 가 (ga)
- (topic marker) 는 (neun)