1. 합니다: comes from 하다 (to do) + (스)ㅂ니다 (formal polite ending) 입니다: comes from 이다 (to be) + (스)ㅂ니다 (formal polite ending) 2. -이에요/예요 (NOT 에요) comes from -이다 (to be) just like -입니다, but it's a different politeness level. It's the polite informal level. -이다 being an irregular verb, you have to learn by heart how to conjugate it. There are 4 politeness levels. -(이)야 (plain informal) -이에요/예요 (polite informal) -(이)다 (just like the dictionary form, plain formal) -(이)ㅂ니다 (polite formal) Note that -이다 is always written together with the previous noun. 오리 (duck) = 오리야 < 오리예요 < 오리다 < 오립니다. 3. 해요 comes from 하다 (to do) just like 합니다. So same explanation as above (#2). 해 < 해요 < 하다 < 합니다. 하다 is often combined with nouns to make verbs. 공부 (study) + 하다 = 공부하다 (to study) 요리 (cooking) + 하다 = 요리하다 (to cook) 4. -(으)니까 is a verb ending indicating a reason, usually followed by an imperative form. 듣기 싫으니까 내 이름 부르지 마. I don't want to hear you so don't call my name. But I think you mean -(스)ㅂ니까. It's used to ask questions, same politeness level as (스)ㅂ니다. 지금 몇 십니까? What time is it now? 화장실이 어딥니까? Where is the bathroom?

1. For examples, "저는 맥스입니다." Means "I'm Max." "저는 맥스라고 합니다." Is more like "I'm called as Max. Or People call me Max." "이에요. 에요." Both are using after "이다, 아니다." And there is different situations to use it. For examples, "아니다+이에요 = 아니에요." If you say "아니이에요." There's two "이". And it sounds weird, that is why you have to drop "이". "집이다+이에요 = 집이에요." Is the same case. But when you use "이에요" to an apple, you don't have to lose "이". For example, "사과다+이에요 = 사과이에요 -> 사과예요.(준말)" And when you use "이에요" after the word ends with "받침", you can not make it short to "준말". For example, "그것은 이불이에요." -> "그것은 이불예요.(x)" "해요." Is "하다 +요." It is a polite way to say "하다." Like "합니다." For example, ”난 맥스라고 한다. 난 맥스라고 해." -> "전 맥스라고 해요." 니까. Is for making sentences explaining reason. Such as "널 사랑하니까. (because, I love you.) I know my poor English made you hard to understand, but please excuse me for my effort.