Everything Starts With the Stem
Korean verbs are listed in the dictionary in the 다 form. Remove 다 and you have the stem, and every ending attaches to that stem.
That is the whole system in miniature: one stem, many endings. The difficulty is not the concept but the sound changes that happen where stem and ending meet.
The Polite Present: 아요 / 어요
Look at the final vowel of the stem. If it is ㅏ or ㅗ, add 아요. For every other vowel, add 어요. 하다 verbs become 해요.
Vowel contractions you must know
Past and Future
The past tense uses the same vowel logic, with 았/었 inserted before the ending. The future uses a modifier plus 거예요.
The Irregulars, One by One
Not every stem ending in ㅂ is irregular
입다 (to wear), 잡다 (to grab) and 씻다 behave regularly: 입어요, 잡아요, 씻어요. Learn the irregulars as a closed list rather than applying the rule to everything that looks similar.
The Honorific Layer
Add 시 to the stem before the ending when the subject is someone you respect. Some verbs also have a separate honorific word.
Practice
Conjugate each verb into the polite present, past and future.
- 보다 (to see)
- 기다리다 (to wait)
- 춥다 (to be cold)
- 듣다 (to listen)
- 공부하다 (to study)
Once the forms are automatic, put them in sentences with Korean sentence structure, then add negation.
FAQ
What is the difference between 아요 and 어요?
The choice depends on the last vowel of the stem: ㅏ or ㅗ take 아요, all other vowels take 어요, and 하다 verbs become 해요. Most of the apparent complexity comes from the vowel contractions that follow.
Why does 춥다 become 추워요?
Because ㅂ is irregular. Before a vowel ending, ㅂ changes to 우, so 춥 + 어요 becomes 추우어요 and then contracts to 추워요. 돕다 follows the same pattern but uses 오: 도와요.
How many irregular verbs are there?
Seven main groups, but only a few dozen verbs in each. Learn them as a list with one model example per group rather than trying to predict which stems are irregular.
Do I need the formal 합니다 form?
Yes for presentations, news, the military and many workplace settings. Learn 해요 style first for conversation, then add 합니다 style as a second register once the endings are automatic.