Not and cannot: 안 and 못

안: I do not

The simplest negation in Korean is the word 안 placed directly in front of the verb or adjective: 먹어요 → 안 먹어요 I do not eat, 가요 → 안 가요, 비싸요 → 안 비싸요 it is not expensive, 바빠요 → 안 바빠요. Nothing else in the sentence changes. With a 하다 verb the 안 slips between the noun and 하다: 공부해요 → 공부 안 해요, 운동해요 → 운동 안 해요. The only verbs that refuse 안 are the two you already negate differently: 있어요 → 없어요, 이에요 → 이/가 아니에요.

못: I cannot

못 sits in the same place as 안 but means cannot or fail to: 못 가요 I cannot go, 못 먹어요 I cannot eat it, 수영을 못 해요 I cannot swim. The difference is will against ability: 안 먹어요 is a choice, 못 먹어요 is an allergy, a full stomach or a food you were never able to eat. Because ability is not a matter of adjectives, 못 goes only with verbs; an adjective takes 안 alone. The adverbs 별로 not particularly and 전혀 not at all need a negation to lean on: 별로 안 비싸요, 전혀 안 어려워요.

저는 아침을 안 먹어요I do not eat breakfast.

오늘은 못 가요I cannot go today.