Korean marks what a sentence is ABOUT with 은/는 and what performs the verb with 이/가. Use 은 and 이 after a consonant, 는 and 가 after a vowel. 는 often carries a sense of contrast, which is why 저는 sounds like "as for me".
Examples
- 저는 학생이에요.
- I'm a student.
- 이름이 뭐예요?
- What is your name?
- 친구는 의사예요.
- My friend is a doctor.
The mistake to avoid
은/는 and 이/가 are not interchangeable - swapping them changes what the sentence is emphasising.
Where this fits in
인사와 자기소개, Korean A1: Greet someone, give your name, ask theirs, and say where you're from in Korean.