The -기 Nominalizer (먹기 싫다, -기 쉽다)

Korean has three ways to turn a verb into a noun — -기, -(으)ㅁ, and -는 것 — and they are not interchangeable. -기 is the one that names an activity: not a fact that happened, but the doing of something, considered as an undertaking. That is why it clusters around feelings, judgments, and — above all — how easy or hard something is. 수영하기 is "swimming (as an activity)," and 수영하기 좋아해요 is "I like swimming." Attach -기 to any verb or adjective stem and you get an activity-noun you can love, hate, start, finish, or find difficult.

What -기 does: it names the activity

Add -기 straight onto the stem — no vowel-harmony choice, no irregular fuss, it attaches to every stem the same way: 먹다 → 먹기, 가다 → 가기, 수영하다 → 수영하기, 읽다 → 읽기, 어렵다 → 어렵기. The result behaves as a noun and takes ordinary particles (이/가, 을/를, 은/는).

찍기 is "the activity of taking (photos)," marked with 를 as the object of 좋아하다. The whole point of -기 is that it packages an activity into something you can have an attitude about.

The signature use: ease and difficulty

If you learn only one -기 pattern, make it -기(가) 쉽다 / 어렵다 ("easy / hard to VERB"). This is a fixed, idiomatic collocation — the activity-noun is the thing that is easy or hard, and the subject particle is usually 가 (often dropped in speech).

Notice the structure: the activity-noun (배우기, 읽기, 끊기) is the grammatical subject of 어렵다/쉽다, and the thing being learned/read/quit keeps its own particle (한국어는, 이 책은, 담배를). This is the natural, native way to say "easy/hard to X" — not a 것-clause.

Feelings about an activity: 좋다, 싫다

The same activity-framing runs through predicates of liking and disliking. 만나기(가) 싫다 is "to not want to meet," where 만나기 is the disliked activity.

Here the reason -기 (not -는 것) is idiomatic is that you are reacting to the prospect of the activity itself, not to a fact in the world.

Wishes and hopes: -기(를) 바라다

The prospective flavor of -기 makes it the natural nominalizer for wishing — you hope for an activity or state that has not yet come true, which is exactly the unrealized territory -기 lives in. The frame is -기(를) 바라다 ("hope that…"), extremely common in cards, announcements, and polite good wishes.

Because you are wishing for an unrealized outcome, -는 것 feels wrong here and -(으)ㅁ (a fact) is impossible — you cannot state as a settled fact something you are only hoping for. This is the clearest demonstration of why -기 is the "prospective" nominalizer.

-기 is welded inside fixed patterns

Beyond standalone nominalization, -기 is the mandatory glue inside a family of high-frequency grammar patterns. In each, the -기 is not optional — the pattern simply requires it:

"Before sleeping" is 자기 전에 — the verb must nominalize with -기 first:

Learn these as whole units. The -기 is doing the same nominalizing work in every one, but you will meet them so often that they feel like single words. The related decision/choice frame -기로 하다 and its cousins are treated on -기로 / -을지 embedded choices.

Why not -는 것 or -(으)ㅁ here?

All three nominalizers exist, but each has a home register and flavor. -는 것 is the everyday, all-purpose choice; -(으)ㅁ is the formal, written "fact" nominalizer; -기 owns the activity-and-evaluation territory above. In the set collocations — 읽기(가) 쉽다, 자기 전에, -기 때문에 — only -기 is idiomatic, even though a 것-clause might be grammatically parseable. The full three-way comparison lives on -기 vs. -(으)ㅁ vs. -는 것; the written-fact nominalizer has its own page, -(으)ㅁ.

Common Mistakes

1. Omitting the -기 inside a fixed pattern. "Before eating" must nominalize the verb: 먹기 전에. Learners often carry over an attributive ending (×먹는 전에) or the bare stem.

2. Swapping in -는 것 for the set ease/difficulty phrase. 읽는 것이 쉽다 is not ungrammatical, but the fixed, idiomatic collocation is 읽기(가) 쉽다 — that is what natives actually say.

3. Adding vowel harmony or an irregular change to -기. -기 attaches identically to every stem — there is no 아/어 choice and no ㅂ/ㄷ irregularity triggered. 어렵다 → 어렵기 (not ×어려기), 듣다 → 듣기 (not ×들기).

4. Using -기 for a stated fact. For "I know that he came" — a fact in the world, not an activity — Korean uses -는 것 / -다는 것, not -기 (×그가 온 것을… is right; ×그가 오기를 안다 is wrong for that meaning). Keep -기 for activities you evaluate, want, or slot into the fixed patterns.

Key Takeaways

• -기 names an activity — the doing of something — and attaches uniformly to any stem: 먹기, 가기, 읽기, 수영하기.
• It is the idiomatic nominalizer with ease/difficulty (쉽다/어렵다) and emotion (좋다/싫다/바라다), and it leans prospective/unrealized.
• It is mandatory glue inside -기 전에, -기 때문에, -기 위해(서), -기로 하다, -기 시작하다 — learn these as units.
• For neutral, everyday nominalization use -는 것; for formal "fact" nominals use -(으)ㅁ. Only -기 fits the set ease/emotion collocations.