Have you ever felt like your opponent was overwhelming you with threats? Every move he makes, he’s attacking something on the board. You make a move to defend it, then he creates another attack. With no time to breathe and make your own threats, you eventually make a mistake, or your opponent plays a forcing series of moves and ends up in a better position than you, which he then converts into a win. You have probably fallen into the cycle of “passive defense”.
There are two kinds of defense in chess: passive vs. active defense. Passive defense is when your opponent makes a threat and your response to the threat does nothing active. In this case you are making a purely defensive move. The best kind of defense to play is active defense. This is when your opponent makes a threat and your response does something active in your position. You may be able to move the attacked piece and create your own threat. Or maybe you tie down the opponent’s attacking piece to defending something more important.
The position above is taken from the game Larry Remlinger vs Melikset Khachiyan (2011). Black is ahead on material, but White has a very active position. The rook is well-placed on d5, attacking the g5 and c5 pawns. Black has another weak pawn on a5 as well. Black could play passively, defending one of the pawns with moves such as Bf6 or Rfc8. White would then enjoy a fine position after capturing the undefended pawn, then targeting the other weak pawns using a combination of his bishops and rook. Even though Black is ahead the exchange, there are not many files open for the rooks to use in the resulting position.
However, in this difficult position position, Black has the possibility of active defense with the move f5! This move attacks the e4 pawn, and if White decided to capture the f5 pawn with exf5 or Rxf5, then the move e6 takes advantage of the pin along the f-file. Through a few pawn trades, Black will be able to open up additional files for his rooks to use and achieve a much more active position. This would be a much better move than a passive defense move such as Bf6 or Rfc8.
Many of these active defenses are tied into tactics and always having a never-give-up attitude. So, whenever you are put on the defensive, look for your chances and strive to keep as active a position as possible!
Read more about general chess principles: “Two Reasons for Castling”.