You really need it explained? Ok. When you walk into the voting booth, and you cast a vote for John Smith, your vote is for John Smith. It does not magically become or equate to a vote for Romney or Obama, nor does it magically become or equate to “taking votes away” from either of them. Your vote is only for the person you pull the lever for.
Ah, didn’t realize you were choosing to be obtuse.
A vote not cast is a vote by the opposition that COUNTS!!! Got it, tis not rocket science.