Man-to-man defense assigns each defender a specific opponent to guard wherever that opponent goes on the court.
Man to man is the default grammar of basketball defence. Each defender owns an opponent and follows them through screens, cuts, and relocations, with help rotating from teammates when the primary defender is beaten. The scheme's vocabulary is the sport's: on ball defence, help and recover, closeouts, and the switch, in which two defenders exchange assignments to neutralize a screen.
For most of NBA history it was nearly the only legal option, since the league's illegal defence rules effectively banned true zones until 2001, so the great defensive teams of the twentieth century, the Russell Celtics, the Bad Boys era Pistons' successors in the 1990s Knicks and Bulls, built their identities inside man to man principles and physical perimeter pressure.
The modern version is really a spectrum: drop coverage, switching, and soft hedges are man to man schemes tuned to the pick and roll era, and the phrase still signals personal accountability. In quiz stems, man to man against zone is the classic tactical contrast, and the correct answer often turns on the 2001 rule change that finally let NBA coaches answer great offences with an honest zone.
In use"They stayed in man-to-man defense for the final possession and switched every screen."