Korean makes a distinction that English doesn't: the difference between an action in progress and a state that results from a completed action.
Both translate to English "am/is/are + verb-ing" but they work very differently.
~고 있다: action in progress
Verb stem + 고 있다 = currently doing [action]
밥을 먹고 있어요. I'm eating. (the action of eating is happening) 공부하고 있어요. I'm studying. (studying is in progress) 전화하고 있어요. I'm on the phone. (calling is happening right now) 비가 오고 있어요. It's raining. (raining is in progress)
This is like English "-ing" for continuous actions. Straightforward.
~아/어 있다: state resulting from completed action
Verb stem + 아/어 있다 = in a state caused by a past action
This is used with intransitive positional or state-change verbs to describe the state you're currently in.
앉아 있어요. I'm sitting. (I sat down and remain in that state) 누워 있어요. I'm lying down. (I lay down and remain there) 서 있어요. I'm standing. (I stood up and remain standing) 열려 있어요. It's open. (someone opened it, and it remains open) 닫혀 있어요. It's closed. (it was closed, and remains closed) 꽂혀 있어요. It's stuck/plugged in. (it was inserted, remains there)
Why the distinction matters
Here's where learners go wrong:
❌ 앉고 있어요: grammatically possible but weird: sounds like you're actively performing the act of sitting down in an ongoing loop ✓ 앉아 있어요: you sat down and you're in that position
❌ 문이 열고 있어요: wrong particle/conjugation entirely ✓ 문이 열려 있어요: the door is open (in a state of being open)
The verbs that take ~아/어 있다 are typically:
- Position verbs: 앉다 (sit), 서다 (stand), 눕다 (lie down)
- State-change verbs: 열다/열리다 (open), 닫다/닫히다 (close), 입다 (wear), 신다 (put on shoes)
Wearing clothes: 입고 있다 vs 입어 있다
This is a famous confusion point:
입고 있어요 : I'm putting on clothes / I'm in the process of dressing
입어 있어요 : technically incorrect; native speakers don't use this
For "wearing" (the resulting state): 입고 있어요 is correct for BOTH "putting on" AND "wearing." Context clarifies.
지금 코트를 입고 있어요. I'm putting on my coat. (action) 코트를 입고 있어요. I'm wearing a coat. (state: same form, different context)
Shoes: 신고 있어요 (wearing/putting on shoes) Glasses: 쓰고 있어요 (wearing/putting on glasses) Hat: 쓰고 있어요 (wearing a hat)
Summary table
| Situation | Pattern | Example |
|---|---|---|
| Action happening now | ~고 있다 | 먹고 있어요 |
| Positional state | ~아/어 있다 | 앉아 있어요 |
| Door/window state | ~아/어 있다 | 열려 있어요 |
| Wearing clothes | ~고 있다 | 입고 있어요 |
This distinction is subtle but Koreans notice when it's wrong. The patterns become intuitive through listening to large amounts of Korean: your brain starts to feel when something sounds off.
A structured Korean course has drills specifically for aspect patterns. Structured Korean courses usually introduce this distinction at the intermediate level, which is exactly where you need it.