The Korean Writing SystemSyllablesNounsPredicatesFormal and Informal SpeechPre-Final and Final EndingsSpeech LevelAdding ㅓ or ㅏ to a predicate stemWords with 받침Adding 으 to predicates stemsThe Deferential Speech LevelThe Intimate Speech LevelThe Polite Speech LevelThe Plain Speech LevelThe Honorific Ending 시Irregular PredicatesParticlesThe Subject Particle 가 and 이The object particle 를 and 을The Topic Particle 는 and 은Forming a Sentence이다 and 아니다있다 and 없다NegationPast TensePredicates as ModifiersDeterminersBound NounsExpressing desire with 고 싶다NumbersCountersQuestionsThe Particle 에The Plural Particle 들The Possessive Particle 의The Particle 에서The Particle 도The Particle 부터The Particle 까지The Particle 만

이다 and 아니다

The copula and  attach directly to a noun. 이다 and 아니다 are antonyms. 이다 indicates that the subject of the clause is equivalent to the noun it attaches to. 아니다 indicates that the subject of the clause is not equivalent to the noun it attaches to.
 
A dog is not a cat.
 
Our daughter is a student.
이다 and 아니다 are conjugated irregularly in the polite and intimate speech level.
follows a noun which ends in a consonant in the intimate speech level.
  
I will introduce (him). He is my younger brother.
야 follows a noun which ends in a vowel in the intimate speech level.
  
Where are you now?
이에요 follows a noun which ends in a consonant in the polite speech level.
 
Is your hometown Daejon?
예요 follows a noun which ends in a vowel in the polite speech level.
   예요
Teacher, what's this part blocked by the paper?
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