Learn Hardcore Korean: yeohaengeun bissayo.

은/는 marks the topic, i.e., what you’re talking about. Here, it sets up “travel” as the topic: “As for travel…”
It can carry a contrastive nuance: “Travel, (on the other hand,) is expensive.”
You choose 은 after a noun ending in a consonant sound and 는 after a vowel sound. 여행 ends with the consonant/ng sound, so 여행은 is correct. If the noun ended in a vowel (e.g., 휴가), you’d say 휴가는.

Why not 여행이 비싸요?

이/가 marks the grammatical subject and often highlights or identifies it.
여행이 비싸요 can sound like “It’s travel that’s expensive” (e.g., answering “What is expensive?”).
여행은 비싸요 presents “travel” as the topic and makes a general statement. Both are grammatical; the nuance differs (topic/general vs. focus/identification).

Can I say 여행을 비싸요?

No. 비싸다 is a descriptive verb (“to be expensive”) and does not take a direct object. The object particle 을/를 is used with action verbs that act on an object, not with adjectives/descriptive verbs like 비싸다.

Is 비싸요 an adjective or a verb in Korean?

In Korean, “adjectives” are treated as descriptive verbs. 비싸요 is the polite present form of the descriptive verb 비싸다 (“to be expensive”). You don’t add the copula (이에요/예요)—여행은 비싸요 is already a complete sentence.

What’s the dictionary form of 비싸요, and how does it conjugate?

Dictionary form: 비싸다
Polite present: 비싸요 (stem 비싸-
- 아요 → 비싸요)
Formal present: 비쌉니다
Casual present: 비싸
Past: 비쌌어요
Future/guess: 비쌀 거예요
Negative: 안 비싸요 / 비싸지 않아요
Attributive (before a noun): 비싼 (e.g., 비싼 호텔 “an expensive hotel”)

Why isn’t it 비싼요?

비싼 is the prenominal (attributive) form used before nouns: 비싼 여행 (“an expensive trip”). At the end of a sentence you need a verb ending, hence 비싸요. For example:

비싼 여행이에요. = “It is an expensive trip.”
여행은 비싸요. = “Travel is expensive.”

Does this mean “Travel is expensive” in general, or “This trip is expensive”?

By default, 여행은 비싸요 reads as a general statement (“Travel/Traveling is expensive”). To specify a particular trip, add context:

이번 여행은 비싸요. = “This trip is expensive.”

When would I prefer 여행은 비싸요 vs. 여행이 비싸요?

Use 여행은 비싸요 to introduce or talk about travel as a topic, often making a general or contrastive point.
Use 여행이 비싸요 to highlight that “travel” (as opposed to something else) is the thing that’s expensive, e.g., in direct answer to “What is expensive?”

How do I turn it into a question: “Is travel expensive?”

여행은 비싸요? (polite, conversational) with rising intonation.
More formal: 여행은 비쌉니까?
If the context is clear, you can simply ask: 비싸요?

How do I say “Traveling is expensive” more explicitly?

여행하는 건 비싸요.
여행하기는 비싸요. (slightly contrastive/emphatic)
A very natural alternative expressing cost: 여행은 돈이 많이 들어요. (“Travel costs a lot of money.”)

Why is there no “to be” like 이에요/예요 in this sentence?

Because 비싸다 already means “to be expensive.” Korean descriptive verbs include the notion of “to be,” so you don’t add 이다. 여행은 비싸요 is complete as is.

How do I negate or change the tense?

Negative: 여행은 안 비싸요 / 여행은 비싸지 않아요
Past: 여행은 비쌌어요
Future/expectation: 여행은 비쌀 거예요
“On the expensive side”: 여행은 비싼 편이에요

What are the pronunciation tips?

여행은 roughly “yeo-haeng-eun.” The final -ng sound in 행 connects smoothly to 은.
비싸요 is “bi-ssa-yo,” with a tense/doubled ss sound. Keep the ss crisp; don’t reduce it to a single s.

Do I always need the polite -요?

Use -요 (e.g., 비싸요) in most everyday polite situations. With close friends or younger people, you can drop it: 여행은 비싸. In formal settings, use 비쌉니다.

Can I replace 은 with 도 to say “Travel is also expensive”?

Yes: 여행도 비싸요 = “Travel is expensive, too.” That adds an “also” meaning compared to something previously mentioned.

What’s the difference between 여행 and 여행하다?

여행 is the noun “travel/trip.”
여행하다 is the verb “to travel.” To say “Traveling is expensive,” you can nominalize the verb: 여행하는 것(=건) or 여행하기 (e.g., 여행하는 건 비싸요).

Are there more natural ways to specify what’s expensive?

Yes, Korean often names the specific cost:

항공권이 비싸요. = “Airfare is expensive.”
숙소가 비싸요. = “Accommodation is expensive.”
여행 경비가 많이 들어요. = “Travel expenses cost a lot.”

Any common mistakes to avoid?

Don’t say 여행을 비싸요 (wrong object marking).
Don’t say 여행은 비싼다 (the -ㄴ다 form isn’t used with descriptive verbs in this way). Use 여행은 비싸다 (plain) or 여행은 비싸요 (polite).
Keep 은/는 attached to the noun with no space: 여행은, not 여행 은.