The defensive three‑second rule limits bigs from camping in the paint, opening lanes for drives and cuts to improve flow and watchability.

Defenders without an active matchup can’t remain in the restricted area for three straight seconds, or it’s a violation.

It reshaped positioning: rim protectors toggle between helping and showing higher; perimeter rotation speeds had to rise.

Combined with the three‑point boom, the league moved faster toward spacing and five‑out; delays, switches, and rotating traps became common.

Offenses adapted too: more spread alignments, weak‑side 45° and corner gravity, and short‑roll playmaking near the stripe.

It’s part of a broader policy arc—alongside hand‑check limits and illegal defense changes—that remapped NBA tactics.