Learn Hardcore Korean: changga jwaseogi bokdo jwaseokboda deo bissayo. - Window seats are more expensive than aisle seats.

이 is the subject marker. In the comparative pattern A이/가 B보다 더 …, A이/가 marks the item being compared (here “the window seat”). So 창가 좌석이 tells us “the window seat” is our comparison target.

What role does 보다 play in this sentence?

보다 is a postposition meaning “than.” It attaches to B, the standard of comparison. Here, 복도 좌석보다 literally means “than the aisle seat.” This 보다 is not the verb “to see,” but the comparative particle.

Why is 더 placed before 비싸요, and what happens if I omit it?

더 means “more” and is used to form comparisons with adjectives that don’t have a built-in comparative.
You can omit 더 (“창가 좌석이 복도 좌석보다 비싸요”) and still be understood—Koreans do this in casual speech—but 더 adds emphasis and clarity.

Can I replace the subject marker 이/가 with the topic marker 은/는?

Yes. Changing 창가 좌석이 to 창가 좌석은 simply makes “window seat” the topic.

창가 좌석은 복도 좌석보다 더 비싸요.
Both versions are correct; the nuance shifts slightly toward general contrast when you use 은/는.

Is there another way to express “than” besides using 보다?

Yes. You can use ~에 비해(서):

창가 좌석이 복도 좌석에 비해 더 비싸요.
This means the same thing but sounds a bit more formal.

Do I always have to mention 복도 좌석보다?

No. If it’s clear from context, you can omit the comparison object:

창가 좌석이 더 비싸요.
This simply states “Window seats are more expensive,” assuming the listener knows “than what.”

Why is the adjective 비싸요 in its polite form? What other endings could I use?

비싸요 is polite present tense ()-요 form.
In informal speech, you’d say 비싸.
In formal writing or announcements, you’d use 비쌉니다.

How is 창가 좌석 constructed? And 복도 좌석?

창가 = 창(window) + 가(side) = window side
복도 = corridor/hallway
좌석 = seat
So 창가 좌석 = window-side seat (window seat), 복도 좌석 = corridor seat (aisle seat).