Korean Particle 은/는 vs 이/가: Topic vs Subject — The Core Difference

은/는 marks known/old information (topic). 이/가 marks new/unknown information (subject). This distinction doesn't exist in English.

The Rule

은/는 marks known/old information (topic). 이/가 marks new/unknown information (subject). This distinction doesn't exist in English. Particles are the backbone of Korean grammar. Unlike English, which relies on word order to show who does what, Korean uses small markers attached directly to nouns. 은/는 vs 이/가 is one of the most fundamental particles you'll encounter, and understanding it correctly will dramatically improve your Korean comprehension.

Why English Speakers Get It Wrong

English doesn't have particles like 은/는 vs 이/가. In English, word order and prepositions do the job — "I gave the book to him" uses position and "to" to clarify meaning. Korean particles attach directly to nouns and change the grammatical role, which feels alien at first. The biggest confusion comes from trying to translate particles one-to-one with English prepositions. 은/는 vs 이/가 doesn't map neatly to any single English word. Instead, think of it as a grammatical tag that tells you the noun's role in the sentence.

How It Works

은/는 marks known/old information (topic). 이/가 marks new/unknown information (subject). This distinction doesn't exist in English. When comparing 은/는 vs 이/가, the key is the NUANCE difference, not the translation. Both might translate the same way in English, but Korean speakers choose between them based on context, emphasis, and what information is new vs. known. Pay attention to how native speakers use 은/는 vs 이/가 in real conversations. You'll start noticing patterns quickly.

Real Examples

• 이 사람이 의사예요. (i sarami uisayeyo.) — "THIS person is a doctor. (new info)" [이/가 = introducing new info] • 이 사람은 의사예요. (i sarameun uisayeyo.) — "This person (we know) is a doctor." [은/는 = about a known topic] • 누가 했어요? — 내가 했어요. (nuga haeteoyo? — naega haeteoyo.) — "Who did it? — I did it." [이/가 for answering 'who']

Common Mistakes

❌ 누가 했어요? — 나는 했어요. (nuga haeteoyo? — naneun haeteoyo.) ✅ 누가 했어요? — 내가 했어요. (nuga haeteoyo? — naega haeteoyo.) → When answering 'who' questions, the answer is new info → use 이/가.

Quick Tip

Practice by labeling objects around you with 은/는 vs 이/가. Say the noun + particle out loud until it feels natural. When reading Korean, circle every 은/는 vs 이/가 you see and ask yourself WHY it was used there — this active reading habit builds intuition faster than memorizing rules.

Remember: 은/는 marks known/old information (topic). 이/가 marks new/unknown information (subject). This distinction doesn't exist in English.

Examples

이 사람이 의사예요. — i sarami uisayeyo. — THIS person is a doctor. (new info)

이 사람은 의사예요. — i sarameun uisayeyo. — This person (we know) is a doctor.

누가 했어요? — 내가 했어요. — nuga haeteoyo? — naega haeteoyo. — Who did it? — I did it.