Subject Marker 이/가

1. What is a Subject Marker?

In English, we usually know who is doing an action based on word order. For example, in "The cat eats the fish," we know the cat is the one eating because it comes before the verb.

Korean, however, relies on particles to define these roles. The subject marker 이/가 attaches to a noun to clearly state that it is the subject of the sentence—the person or thing performing the verb's action or being described by an adjective.

Let's watch a short clip that explains this fundamental difference between English and Korean.

As the video shows, particles like 이/가 give you the freedom to move words around in a sentence without changing the core meaning, because the particle, not the word's position, tells you its role.

2. The Basic Rule: Attaching 이 and 가

Just like with 은/는, there's a simple rule for choosing between 이 and 가. It all depends on whether the noun ends in a consonant or a vowel.

• Use 이 (i) after a noun that ends in a consonant (a final consonant sound, or 받침 [batchim]).
• Use 가 (ga) after a noun that ends in a vowel.

This infographic from the article is a great visual summary:

Let's look at a few more examples:

• 사람 (saram, person) ends with the consonant 'ㅁ', so it becomes 사람이 (saram-i).
• 친구 (chingu, friend) ends with the vowel 'ㅜ', so it becomes 친구가 (chingu-ga).

3. The Core Difference: 이/가 (Subject) vs. 은/는 (Topic)

This is the heart of today's lesson. When do you use the subject marker 이/가, and when do you use the topic marker 은/는 that we learned last time? While a full understanding comes with practice and exposure, we can establish a very clear core distinction.

• 이/가 (Subject Marker): Use this to identify or emphasize the subject. It often introduces new information and answers the question "Who?" or "What?".
• 은/는 (Topic Marker): Use this to introduce a topic of conversation. It often refers to something already known or is used to make a general statement or a comparison.

This next video explains this difference brilliantly using a simple scenario.

Let's break down the video's key point with an example:

1. Someone asks: "누가 왔어요?" (nuga wasseoyo?) - "Who came?"

   • The question uses 가 to ask for the subject's identity.
   • Your answer should also use 이/가 to identify that subject: "친구가 왔어요." (chingu-ga wasseoyo.) - "A friend came."
   • Here, "a friend" is the new, important piece of information.

2. Someone points to your friend and asks: "저 사람은 뭐 해요?" (jeo saram-eun mwo haeyo?) - "As for that person, what are they doing?"

   • The question uses 은 to set the person as the topic.
   • Your answer can continue that topic: "친구는 책을 읽어요." (chingu-neun chaeg-eul ilgeoyo.) - "My friend is reading a book."
   • Here, the action ("reading a book") is the new information, not the friend.

This distinction is also explained very well in the following article.

Key Nuance: Don't worry if this feels a bit tricky at first. It's one of the most nuanced aspects of beginner Korean. Even if you mix them up, people will almost always understand you. The difference is about subtlety and natural flow, which you'll absorb over time.

4. Building Simple Sentences

Now let's practice forming simple sentences. We'll combine a noun + 이/가 with a descriptive word (an adjective or verb).

Notice how in each case, the noun marked with 이/가 is the specific subject being described or doing the action.

The subject marker can be attached to regular nouns, pronouns like 'I' or 'you', and more.

Conclusion

Great job today! You've learned about a fundamental building block of Korean sentences. Properly using the subject marker will make your Korean much clearer and more precise.

Key Takeaways:

• 이/가 is the subject marker. It attaches to a noun to identify it as the performer of an action or the subject of a description.
• The rule is simple: 이 follows a consonant, and 가 follows a vowel.
• The key difference from the topic marker 은/는 is that 이/가 is used to identify or emphasize the subject, often as new information, while 은/는 is used to set a general topic for discussion or comparison.
• Think of 이/가 as answering "Who?" or "What?".

Next Lesson Preview

So far, we've learned how to mark the topic of a sentence (은/는) and the subject of a verb (이/가). We're now ready for the final piece of the basic sentence puzzle: the object. In our next lesson, we will learn how to use the object marker 을/를 to indicate the noun that receives the action of a verb, allowing us to form complete Subject-Object-Verb sentences like "I read a book."