In written Korean for diaries and the like, we aren't always sure who the reader might be and therefore it's awkward to write using endings such as 요 and 습니다. So therefore we use the written form. Present tense verb + (느)ㄴ다 eg. 하다 -> 한다 eg. 먹다 -> 먹는다 Past tense verb + 았/었다 eg. 하다 -> 했다 eg. 먹다 -> 먹었다 Future tense verb + (으)ㄹ 것이다 eg. 하다 -> 할 것이다 eg. 먹다 -> 먹을 것이다 Adverb (dictionary form) eg. 예쁘다 (no change) eg. 귀엽다 (no change)