이다 is the Korean affirmative copula. This is roughly equivalent to the English verb “to be.” Using 이다 is the most useful and basic way to identify people and objects. An example of a sentence is “(Subject and particle) + [Noun]+입니다.” This expresses “(Subject) is [noun].” If the subject is not included in the sentence, the subject must be inferred.
•입니다 (imnida) is the formal simple present conjugation of 이다 (ida).
•이에요 (ieyo) is the standard simple present conjugation of 이다 (ida).
•이야 (iya) is the casual simple present conjugation of 이다 (ida).
•입니까 (imnikka) is the formal interrogative conjugation of 이다 (ida).
I am Peter.
I am a student.
(This) is a chair.
(Subject) is a foreigner.
This (here) is Seoul.
•When conjugated into the formal simple present 이다 becomes 입니다 (imnida). The pronunciation of this is 임니다 (imnida).