A team organizes itself to stop the opposition from scoring. That collective effort is defense. It requires positioning, communication, and disciplined reactions to the ball and attackers.

Defensive systems vary by sport—man-to-man, zone, press, deep block—yet all aim to restrict space and time for the offense. Individual defenders need anticipation, tackling or checking skill, and the ability to recover after being beaten. Set-piece defense often decides close matches.

Strong defense creates the platform for counter-attacks and protects leads. It can also frustrate more talented attacking sides. Coaches spend extensive time drilling defensive shape because a single lapse can undo long periods of good work.

Championship teams are rarely weak at the defensive end.