BB defense is unique in poker because the player already has 1BB invested in the pot, improving their pot odds to call opens from all positions. BB defense frequency must be calibrated to prevent steals from being immediately profitable for openers. Against late position opens (BTN, CO), BB can defend with very wide ranges (55-65%), while against EP opens, defense should be more restricted (30-40%). Beyond calls, BB must include 3bets in their defense strategy, both for value and as bluffs, to prevent openers from having excessive fold equity against their range.