The two basic defenses in basketball are man-to-man, sometimes referred to as person-to-person in respect for the rise of women's basketball, and zone. Each basic defense has a number of variations. Many coaches prefer the man-to-man defense since it generally is a more aggressive style. However, the legendary John Wooden, who coached UCLA to an unmatched 10 National Collegiate Athletic Conference championships, used both man-to-man and a ferocious full court zone trap. A team that plays both man-to-man and zone defenses effectively is well-suited to guard against any type of offense.
In a classic man-to-man defense, the coach assigns each player to guard a specific offensive player. If you are playing a full court man-to-man defense, you pick up your assigned player as soon the other team controls the ball. If you are playing half-court man-to-man, you retreat to the defensive side of the court and pick up your man soon after he crosses the center line.
Two main variations exist within the man-to-man defense. The first is a switching man-to-man. When an offensive man sets a screen on you, you switch and pick up the person setting the screen while defender who was guarding that person picks up your man. Switching screens is somewhat of an art form in the National Basketball Association, where the pick-and-roll is the main offensive weapon. The second variation is the sagging man-to-man, in which some of the defenders drop back from their defenders. They can apply this when some of the offensive players are weak shooters from the outside, or to make it easier to defend against a shot when an offensive player beats his man on the dribble.
If your team is playing zone, you guard a particular area instead of a particular man. When an offensive player enters your zone, it is your responsibility to pick him up. When he leaves your zone, your teammate who patrols that zone picks him up. Zone defenses are useful when the opposition shoots poorly from the outside, or when the opposition has a quickness edge and can blow by your defenders on the dribble.
Many variations of zone defense exist.The standard zone is a 2-1-2, with two defenders patrolling the outside, one defender in the middle around the foul line and two defenders on the inside. A 2-3 zone, with three defenders on the back line, is a strong rebounding formation. A 1-2-2 zone allows you to put more pressure on the ball. Zones can be very passive or very active. Many types of half-court and full-court zone formations can trap opponents and pressure them into turnovers.