Clearance Sacrifce

Sacrifice is crucial in every aspect and same holds true in the game of Chess.
Sometimes, you have a very attacking plan in your mind but due to non availability of a specific square, you are not able to apply it. So making a sacrifice, in order to clear the way for your plan is known as CLEARANCE SACRIFICE.
For e.g. in diagram, White clears its square King 5 by sacrificing Knight. Though this move seems senseless but it was necessary and further it is followed by a Queen sacrifice. So after these two senseless moves, the Black is subjected to double Check and a Check mate. So now you can say, these weren't senseless moves.