Well deck in the context of "Ivan Rogov-class landing ship"

An amphibious assault ship is a type of amphibious warfare ship designed for spearheading amphibious incursions of marines into enemy territories during an armed conflict, via launching either naval landings or air assaults and also by providing shipborne close air support and logistics for landed friendly forces. Such a ship is typically the capital ship of a dedicated fleet known as the amphibious ready group or expeditionary strike group.

Amphibious assault ships evolved from aircraft carriers converted for specific use as helicopter carriers, which, as a result, are often mistaken for conventional fixed-wing aircraft carriers. Like the aircraft carriers they were developed from, some amphibious assault ships also support V/STOL fixed-wing aircraft, and some latest models (e.g. China's Type 076) have catapult systems for assisted takeoff of fixed-wing light aircraft such as UCAVs and have a secondary role as drone carriers. Most modern AAS designs also carry landing craft with most including a well deck, usually at the stern, to support large LCACs (hovercraft) and LCUs, which can insert both infantry and combat vehicles directly onto land.

An amphibious transport dock, also called a landing platform dock (LPD), is an amphibious warfare ship, a warship that embarks, transports, and lands elements of a landing force for expeditionary warfare missions. Several navies currently operate this kind of ship. The ships are generally designed to transport troops into a war zone by sea, primarily using landing craft, although invariably they also have the capability to operate transport helicopters.

Amphibious transport docks perform the mission of amphibious transports, amphibious cargo ships, and the older dock landing ships (LSD) by incorporating both a flight deck and a well deck that can be ballasted and deballasted to support landing craft or amphibious vehicles. The main difference between LSDs and LPDs is that while both have helicopter landing decks, the LPD also has hangar facilities for protection and maintenance. In the United States Navy, the newer class of LPD has succeeded the older classes of LSDs, and both the Navy and United States Marine Corps are looking to the LPD to be the basis of their new LX(R) program to replace their LSDs.