The best defense is a good offense
"The best defense is a good offense" is an adage that has been applied to many fields of endeavor, including games and military combat. Generally the idea is that offensive action preoccupies the opposition and ultimately its ability to directly harm.
Mao Zedong opined that "the only real defense is active defense", meaning defense for the purpose of counter-attacking and taking the offensive. Often success rests on destroying the enemy's ability to attack. This principle is parelleled in the writings of Machiavelli and Sun Tzu.
It basically means, the executing a defensive style can lead to a good counter attack "offense" and in thus the best defense will lead to a great offense.
In some board games, such as Risk, one's ability to build up armies depends on aggressively attacking so as to acquire territory; however, in Risk, luck in rolling the dice is the ultimate determining factor. Players who fail to do so, and concentrate instead on holding the line against enemy attack, will likely end up in a weak position. In-depth info argues that this adage does not always apply: "When the battle rages between two players one should put every ounce of power in the offense, but when several players are involved, the political element changes this dynamic." In chess, one's ability to prevent enemy attacks often depends on maintaining the initiative – i.e., making a series of threats that the opponent must use his turns to parry, rather than launching his own attacks; thus, common tips used in conjunction with this adage are that the best way to upset your opponent’s plans is to become menacing and that the best way to stop an enemy threat to your own king is to attack his.
In StarCraft II: Wings of Liberty's multiplayer, protecting one's own bases can be difficult due to the large size of maps and the slow speed of many of the player's units. A player generally has several bases, and so the enemy has several locations he can strike at. Defending each base would require a thin spreading of the player's army, and defending only one would leave the others at risk of destruction. To discourage the enemy from attacking these bases, the player can attack the enemy's bases, forcing the enemy to defend himself or risk defeat. In turn, the enemy can attack the player's bases, preventing this attack. Games are generally composed of a series of "pushes," or attacks, and "counter-pushes," or counter-attacks, in which each player attempts to destroy the other's army to prevent their base from being attacked and to allow themselves to attack the enemy's base without risk.
In sports such as soccer and basketball, the adage is used to note that success can hinge on an effective offense that keeps the ball on the other team's side of the field, thus not only creating scoring opportunities but preventing the opposing team from scoring.