In naval architecture an afterdeck or after deck, or sometimes the aftdeck, aft deck or a-deck, is the open deck area toward the stern or aft back part of a ship or boat. The afterdeck can be used for a number of different purposes. Not all ships have an afterdeck. In place of the afterdeck a ship may be built with a poop deck, that is a deck that forms the roof of a cabin built in the rear, or "aft", part of the superstructure of a ship. A poop deck usually is higher up than an afterdeck. A ship may have its superstructure or aftercastle located in the stern and thus not have an afterdeck. The stern and afterdeck of a ship are usually more smooth and stable than the bow (front) of the ship in motion. A taffrail is the handrail around the open afterdeck or poop deck. On wooden sailing ships like man-of-war or East Indiaman the taffrail is usually a hand carved wood rail and often highly decorated.  
HMNZS Canterbury with a large aftdeck for helicopters.
HMNZS Canterbury's helicopter afterdeck.
President Truman and members of his staff relaxing on the afterdeck of the yacht USS Williamsburg.
After deck of USS Manchester.
After deck of Abeille Bourbon.
Sailors on the afterdeck of HTMS Nakha.
Aftdeck pool on Golden Princess.
Missile boat with missile launching on the after deck.
After deck of a UK Rescue Lifeboat 17-31.