The knight move is unusual among chess pieces. Unlike all other standard chess pieces, the knight can 'jump over' all other pawns and pieces (of either color) to its destination square. The knight's ability to 'jump over' other pieces means it is at its most powerful in closed positions.

A knight should always be close to where the action is. Pieces are generally more powerful if placed near the center of the board, but this is particularly true for a knight.

Taken from Wikipedia