1. -요.

    1. '-요' is a polite, informal verb ending.
    2. '-요' follows verb roots ending with a vowel.
    3. Both questions and statement can end with '-요' in Korean.
      They are differentiated only by intonation.
    4. A verb can be a complete sentence in korean.
      가|요?
      가|요.      		 Do (you) go ?
      (I) go.
      만나|요?
      만나|요.      		 Do (you) meet (him) ?
      (I) meet (him).

  2. -세요 ?

    1. '-세요?' is more polite than '-요?'. It implies respect of the speaker for the subject of the verb.
    2. The answer to '-세요?' is not '-세요' but '-요' when referring to the first person.
      가|세요?
      가|요.      		 Do (you) go ?
      (I) go.
      만나|세요?
      만나|요.      		 Do (you) meet (him) ?
      (I) meet (him).

  3. -세요.

    1. '-세요' means 'Please do -' when referring to the second person.
    2. When referring to the third person, '-세요' is just a polite ending.
      가|세요.
      가|세요.      		 please go.
      (He) goes.
      만나|세요
      만나|세요.      		 please meet (him).
      (she) meets (him).

  4. Unlike in English, there are two basically different ways to say 'Good-bye!'. depending on the situation. To say good-bye, one does not say "안녕하세요", but rather "안녕히 가세요" or "안녕히 계세요", depending on whether the other person is leaving or staying.

    1. If the speakers leaves the place at the same time, both of them say "안녕히 가세요".
    2. If one of the speakers stays in the place, those who are leaving say "안녕히 계세요" to the person who will stay.