Coordination connects equally important ideas. A coordination conjunction is a word that connects words, clauses or phrases in a positive, negative, or neutral way.
Coordination conjunction: Susan forgot to set her alarm, so she overslept.
Subordination link important ideas with ideas that are less important. A subordinated conjunction word that generally connects a particular situation.
Subordinate conjunction: Susan forgot to set her alarm because she was tired.
 Independent clause
It’s simply a complete sentence a sentence that has both a subject and a verb so this sentence can stand alone and that's why we call it independent as opposed to dependent, Example : Susan forgot to set her alarm.  Susan is an subject and forgot is a verb.