Definition from Wiktionary, the free dictionary
- marks the topic of the sentence. The topic of a sentence is not to be confused with the subject of the sentence.
- depending on context, shows contrast with or adds emphasis to the preceding word or phrase in a sentence.
- (topic marker): The topic is what is being talked about in the sentence, it is the main point. This however is different in meaning from the subject which the predicate directly refers to. The topic and subject may be the same in a sentence. For example,
- 매리는 나의 친구다. (Mary-neun na-eui chingu-da.) — “Mary is my friend.”
- In this case "Mary" is the topic (and the subject) of this sentence and "is my friend" is the predicate. However, in many cases, the subject and topic are different.
- (Complete form) 이 반에 있는 학생들은 똑똑하다. (I ban-e itt-neun haksaeng-deul-eun ddokddok-hada.) — The students that are in this class are smart. — Note the use of the first 는/은: function of 는/은 after verbs does not indicate nominative case but the adjectival form of the verb.
- (Shortened form) 이 반은 학생들이 똑똑하다. (I ban-eun haksaengdeul-i ddokddok-hada.) — "The students in this class are smart.”
- Compare the complete and shortened form. Here, the topic/subject distinction is a pseudo-grammatical distinction. All sentences that use both 는/은 and 가/이 can derive its expletive form as shown above.
- In the shortened form, the topic is "This class" while the subject is "the students".
- In cases like this, the topic can often be thought of as a range, or to what extent the sentence is applicable. In the example above, if "speaking of this class" was removed, the sentence would not be limited to "this class", and would talk about all students in general.
- (Contrast/emphasis marker): 는 (neun), can be placed after most case markers (including 가 (ga), 를 (reul), 에 (e), 에게 (ege), 에서 (eseo), 로 (ro), 과 (gwa)) to show contrast between two or more choices or add emphasis to a word or phrase, depending on the context. If used after 가 (ga) or 를 (reul), the 가 (ga) or 를 (reul) are deleted leaving only 은 (eun).
- 서울은 한국의 수도다. (seoul-eun hanguk-eui sudo-da.) — “Seoul is the capital city of South Korea.”
- 여름에는 덥다. (yeoreum-e-neun deopda.) — “It is hot during the summer.”
- 그는 나에게 책을 주었다. (geu-neun na-ege chaeg-eul jueotta.) — “He gave me the book.” (He gave the book to me)
- 은 (eun) (after a consonant)