Verbs as Nouns: -는 것, -기

To use a verb like a noun (walking, cooking, to learn), Korean has two common tools.

• -는 것: verb stem + 는 것 = the act of doing something. Use it for hobbies, likes and general statements: 사진을 찍는 것이에요 (it's taking photos), 걷는 것은 건강에 좋아요 (walking is good for your health). ㄹ-stems drop the ㄹ: 놀다 → 노는 것. In speech 것이 often becomes 게 and 것을 becomes 걸.
• -기: verb stem + 기, used in fixed patterns: -기가 쉽다 / 어렵다 / 편하다 (easy / hard / comfortable to do), -기 시작하다 (to start doing), -기로 하다 (to decide to do), -기가 싫다 (not to want to do), -기를 좋아하다 (to like doing).
• Examples: 한국어는 배우기가 쉬워요 (Korean is easy to learn), 비가 오기 시작했어요 (it started to rain).

Tip: if the gap is followed by 것, use -는; if it is followed by 가, 를, 로 or 시작하다, use -기.