Bishop vs. Knight

I'm fairly new to chess and chess.com. 

I have a question ---  If you have to choose between losing a bishop and losing a knight, which would you prefer? Why? 

How does that relate to your overall style of play? Attacking, defensive, etc??? 

Crawl before you walk is what most people will probably tell you, but if you're new to chess, knowing guidelines/thumb rules actually make sense.

Think of the value of pieces based on what they can do on the board .. AT THAT MOMENT/POSITION in the time.   Just because a queen can move limitlessly and dominate so many squares doesn't mean she does so from the get-go. 

Different positions favor different pieces.

Now If a position is too cluttered or locked up, ask => which piece (Knight or Bishop) will feel more claustrophobic? Evidently a bishop. So I'd probably trade a bishop for knight in that scenario. If the board is wide open with long diagonals that give the bishop more squares, the bishop rules over the "slow" moving knight.

Now often enough, even the closed + locked up positions (usually favoring Knights) tend to open up eventually (most roads DO lead to an endgame!) so the bishop tends to have better odds of being a favored piece overall.

Hope this helps. 

It's positionally subjective.  Even in open positions the Bishop can be dominated by the Knight:

That "final answer to end all questions" post was funny :)

Let's not lose track of the fact that the OP admits he's a new player in need of thumb rules / guidelines to improve.   During our own development, we've all learned quite a bit of guidelines and then, as we got even stronger, learned when to break them or know all the "exceptions". I think the OP is looking for a little more encouragement to get him past the first few hurdles. I'm sure he'd appreciate the nuances a lot more when he gets stronger.

tonydal you frogot number 3.

3) It is easier to open a position than to close one! Due to the fact that even in "closed" positions pawn structure can be somewhat fluid.

If you want to know more look a some of Bobby's games where he is well known for keeping that light squared bishop no matter what! As well as trading of a "good" knight for bad bishop. He even called it winning the minor exchange.