user11995: I am a chess newbie and I was watching a video on four knights opening and the person was discussing another variation and he said that one is dramatic and quite sharp.  From what I saw, it seems "sharp" means immediate mating threats. 
Wiki has this: 
"Risky, double-edged, highly tactical. Sharp can be used to describe moves, maneuvers, positions, and styles of play."
https://en.wikipedia.org/wiki/Glossary_of_chess#S
That definition, if correct, is still sort of vague for me.  Does it mean Kasparov plays sharp because he was very good at tactics?  Or if you go for Scholar's Mate, does that mean you're using a sharp line?  Can someone elaborate on the meaning of sharp more, like what makes a line sharp, maybe with examples?  Thanks.

user12078: Usually a complex position that has a lot of tactics. A very open-position with lots of pieces usually, or a crowded-closed position. 
It means that players must think extra-hard in every move for potential mistakes and complexities, where each candidate move has a large set of lines that constantly switch positional-advantage.
It could be a position that 6 moves down can lead to White's advantage, but 7 moves down can lead to black's advantage, so it might be worth falling into White's "trap" that is actually a "counter-trap."

user19861: "Sharp" just means tactically complex. 
In a sharp position you may have 2 or 3 moves to choose from and most other moves will lose the game immediately or at least leave you with a significant disadvantage. Generally, the same will be true for your opponent. 
In a quiet position (the opposite of sharp) you could throw pretty much any move out there and it's not going to drastically change things.  

user11684: A sharp position is one where every move is critical and any mistake could be your last; in such positions basic principles take a back seat to calculation. The opposite of a sharp position is a calm position, where you have time to maneuver as you please and arrange your pieces as you want before initiating confrontation.

11995: <p>I am a chess newbie and I was watching a video on four knights opening and the person was discussing another variation and he said that one is dramatic and quite sharp.  From what I saw, it seems "sharp" means immediate mating threats. </p>

<p>Wiki has this: </p>

<p>"Risky, double-edged, highly tactical. Sharp can be used to describe moves, maneuvers, positions, and styles of play."</p>

<p><a href="https://en.wikipedia.org/wiki/Glossary_of_chess#S" rel="noreferrer">https://en.wikipedia.org/wiki/Glossary_of_chess#S</a></p>

<p>That definition, if correct, is still sort of vague for me.  Does it mean Kasparov plays sharp because he was very good at tactics?  Or if you go for Scholar's Mate, does that mean you're using a sharp line?  Can someone elaborate on the meaning of sharp more, like what makes a line sharp, maybe with examples?  Thanks.</p>
 12078: <p>Usually a complex position that has a lot of tactics. A very open-position with lots of pieces usually, or a crowded-closed position. </p>

<p>It means that players must think extra-hard in every move for potential mistakes and complexities, where each candidate move has a large set of lines that constantly switch positional-advantage.</p>

<p>It could be a position that 6 moves down can lead to White's advantage, but 7 moves down can lead to black's advantage, so it might be worth falling into White's "trap" that is actually a "counter-trap."</p>
 19861: <p>"Sharp" just means tactically complex. </p>

<p>In a sharp position you may have 2 or 3 moves to choose from and most other moves will lose the game immediately or at least leave you with a significant disadvantage. Generally, the same will be true for your opponent. </p>

<p>In a quiet position (the opposite of sharp) you could throw pretty much any move out there and it's not going to drastically change things.  </p>
 11684: <p>A sharp position is one where every move is critical and any mistake could be your last; in such positions basic principles take a back seat to calculation. The opposite of a sharp position is a calm position, where you have time to maneuver as you please and arrange your pieces as you want before initiating confrontation.</p>
