Moisture-resistant (green) gypsum board

Moisture-resistant (MR) board is plasterboard with water-repellent additives in its core, conventionally faced in green so trades can tell it apart from standard board. It resists humidity and occasional moisture far better than standard gypsum board (which sags, softens and grows mould in damp/splashed areas), which is why it's the correct choice for bathroom and kitchen ceilings and walls, utility rooms and splash zones. The critical limit to understand: MR board is moisture-RESISTANT, not waterproof — in a directly-wet area (inside a shower, or behind tiles that get soaked) it must NOT be relied on alone; those zones need a proper waterproofing/tanking system applied over the board (a liquid membrane or tanking kit), or a dedicated cement/fibre tile-backer board, before tiling. So the rule is MR (green) board for the damp room plus tanking in the actual wet zone — see the moisture-resistant board thread. A gypsum and finishing specialist specs the board and the waterproofing together.