First choose the form by the noun ending
| Job | After a consonant | After a vowel | Examples |
|---|---|---|---|
| Topic / contrast | 은 | 는 | 책은 · 커피는 |
| Subject | 이 | 가 | 책이 · 커피가 |
| Object | 을 | 를 | 책을 · 커피를 |
A final consonant in a Hangul block is called 받침. 책 has the final consonant ㄱ; 커피 ends in a vowel. That selects the form within each pair. It does not choose the noun’s job. “Does this noun end in a consonant?” and “What does this noun do here?” are two separate questions.
Use one scene to see the roles
You and a friend are in a café. Your friend asks what you drink. You answer:
저는 차를 마셔요.
I drink tea. / As for me, I drink tea.
저는 sets you as the topic. 차를 marks tea as the thing being drunk. 마셔요 is the polite present form of “drink.” Now your friend asks who drinks tea. An answer can be 제가 차를 마셔요. (“I’m the one who drinks tea.”) Here the subject marker helps identify who performs the action. 저 + 가 becomes 제가.
Both sentences are grammatical, but they respond to different conversational needs. Swapping a particle is not just changing a decorative suffix. Read the question before choosing an answer.
Topic and subject can appear together
Consider 이 카페는 커피가 맛있어요. (“At this café, the coffee is delicious.”) 이 카페는 establishes what we are talking about, and 커피가 identifies what is delicious. A sentence can have a topic and a separately marked subject. “Only one of these particles may appear per sentence” would therefore be a misleading rule.
To contrast two drinks, say 커피는 좋아해요. 차는 안 좋아해요. (“I like coffee. I don’t like tea.”) The topic marker highlights a contrast. With 커피를 좋아해요., the object marker instead presents coffee as what you like, without explicitly setting up that contrast.
In conversation, Korean often omits information that is already clear. If someone asks what you drink, 차를 마셔요. can be enough. Practise complete sentences first, then notice omissions in real dialogues. Do not assume that every English “I” or “you” needs to be written in Korean.
Three errors worth catching
| Problem | Better example | Explanation |
|---|---|---|
| 커피을 마셔요. | 커피를 마셔요. | Use 를 because 커피 ends in a vowel. |
| Treating English word order as the only clue | 민수가 책을 읽어요. | 수가 identifies the subject; 책을 identifies what is read. |
| Choosing 은/는 for every subject | 누가 왔어요? 민수가 왔어요. | The reply identifies who came; 이/가 fits that focus. |
The second example means “Minsu reads a book.” Its verb normally comes at the end. Korean allows flexibility in arranging other parts, but beginners should use a straightforward noun–object–verb pattern while learning the particles.
Choose with the whole context
Transfer it to your own sentence
Write “I drink water” with 저, 물, and 마셔요. A model is 저는 물을 마셔요. 물 ends in ㄹ, so it takes 을 as the object. Next replace 물 with 우유: 저는 우유를 마셔요. The noun’s role stays the same; the form changes because its ending changes.
Reference and next step
The National Institute of Korean Language: Korean–English Learners’ Dictionary provides entries for the particles and the verbs 마시다, 읽다, 좋아하다. See also its entry for 은, which describes topic and additional uses. This guide’s café scene and exercises are original examples. Continue with grammar for endings and more sentence patterns.