Aircraft carrier
The angled deck allows the installation of one or two "waist" catapults in addition to the two bow cats. An angled deck also improves launch and recovery cycle flexibility with the option of simultaneous launching and recovery of aircraft.
Conventional ("tailhook") aircraft rely upon a landing signal officer (LSO, radio call sign 'paddles') to monitor the aircraft's approach, visually gauge glideslope, attitude, and airspeed, and transmit that data to the pilot. Before the angled deck emerged in the 1950s, LSOs used colored paddles to signal corrections to the pilot (hence the nickname). From the late 1950s onward, visual landing aids such as the optical landing system have provided information on proper glide slope, but LSOs still transmit voice calls to approaching pilots by radio.
Key personnel involved in the flight deck include the shooters, the handler, and the air boss. Shooters are naval aviators or naval flight officers and are responsible for launching aircraft. The handler works just inside the island from the flight deck and is responsible for the movement of aircraft before launching and after recovery. The "air boss" (usually a commander) occupies the top bridge (Primary Flight Control, also called primary or the tower) and has the overall responsibility for controlling launch, recovery and "those aircraft in the air near the ship, and the movement of planes on the flight deck, which itself resembles a well-choreographed ballet". The captain of the ship spends most of his time one level below primary on the Navigation Bridge. Below this is the Flag Bridge, designated for the embarked admiral and his staff.
To facilitate working on the flight deck of a US aircraft carrier, the sailors wear colored shirts that designate their responsibilities. There are at least seven different colors worn by flight deck personnel for modern United States Navy carrier air operations. Carrier operations of other nations use similar color schemes.

Deck structures: The superstructure of a carrier (such as the bridge, flight control tower) are concentrated in a relatively small area called an island, a feature pioneered on HMS Hermes in 1923. While the island is usually built on the starboard side of the flight deck, the Japanese aircraft carriers Akagi and Hiryū had their islands built on the port side. Very few carriers have been designed or built without an island. The flush deck configuration proved to have significant drawbacks, primary of which was management of the exhaust from the power plant. Fumes coming across the deck were a major issue in USS Langley. In addition, lack of an island meant difficulties managing the flight deck, performing air traffic control, a lack of radar housing placements and problems with navigating and controlling the ship itself.
Another deck structure that can be seen is a ski-jump ramp at the forward end of the flight deck. This was first developed to help launch short take off vertical landing (STOVL) aircraft take off at far higher weights than is possible with a vertical or rolling takeoff on flat decks. Originally developed by the Royal Navy, it since has been adopted by many navies for smaller carriers. A ski-jump ramp works by converting some of the forward rolling movement of the aircraft into vertical velocity and is sometimes combined with the aiming of jet thrust partly downward. This allows heavily loaded and fueled aircraft a few more precious seconds to attain sufficient air velocity and lift to sustain normal flight. Without a ski-jump, launching fully-loaded and fueled aircraft such as the Harrier would not be possible on a smaller flat deck ship before either stalling out or crashing directly into the sea.
Although STOVL aircraft are capable of taking off vertically from a spot on the deck, using the ramp and a running start is far more fuel efficient and permits a heavier launch weight. As catapults are unnecessary, carriers with this arrangement reduce weight, complexity, and space needed for complex steam or electromagnetic launching equipment. Vertical landing aircraft also remove the need for arresting cables and related hardware. Russian, Chinese, and Indian carriers include a ski-jump ramp for launching lightly loaded conventional fighter aircraft but recover using traditional carrier arresting cables and a tailhook on their aircraft.
The disadvantage of the ski-jump is the penalty it exacts on aircraft size, payload, and fuel load (and thus range); heavily laden aircraft cannot launch using a ski-jump because their high loaded weight requires either a longer takeoff roll than is possible on a carrier deck, or assistance from a catapult or JATO rocket. For example, the Russian Sukhoi Su-33 is only able to launch from the carrier Admiral Kuznetsov with a minimal armament and fuel load. Another disadvantage is on mixed flight deck operations where helicopters are also present, such as on a US landing helicopter dock or landing helicopter assault amphibious assault ship. A ski jump is not included as this would eliminate one or more helicopter landing areas; this flat deck limits the loading of Harriers but is somewhat mitigated by the longer rolling start provided by a long flight deck compared to many STOVL carriers.

National fleets: The US Navy has the largest fleet of carriers in the world, with eleven supercarriers currently in service. China and India each have two STOBAR carriers in service. The UK has two STOVL carriers in service. The navies of France and Russia each operate a single medium-sized carrier. The US also has nine similarly sized Amphibious Warfare Ships. There are five small light carriers in use capable of operating both fixed-wing aircraft and helicopters; Japan and Italy each operate two, and Spain one.
Additionally there are eighteen small carriers which only operate helicopters serving the navies of Australia (2), Brazil (1), China (2), Egypt (2), France (3), Japan (4), South Korea (2), Thailand (1) and Turkey (1).

Algeria: Current
Kalaat Béni Abbès (L-474) is an amphibious transport dock of the Algerian National Navy with two deck-landing spots for helicopters.

Australia: Current
The Royal Australian Navy operates two Canberra-class landing helicopter docks. The two-ship class, based on the Spanish vessel Juan Carlos I and built by Navantia and BAE Systems Australia, represents the largest ships ever built for the Royal Australian Navy.
HMAS Canberra underwent sea trials in late 2013 and was commissioned in 2014. Her sister ship, HMAS Adelaide, was commissioned in December 2015. The Australian ships retain the ski-ramp from the Juan Carlos I design, although the RAN has not acquired carrier-based fixed-wing aircraft.

Brazil: Current
In December 2017, the Brazilian Navy confirmed the purchase of HMS Ocean for (GBP) £84.6 million (equivalent to R$359.5M and US$113.2M) and renamed her Atlântico. The ship was decommissioned from Royal Navy service in March 2018. The Brazilian Navy commissioned the carrier on 29 June 2018 in the United Kingdom. After undertaking a period of maintenance in the UK, the ship travelled to its new home port, Arsenal de Marinha do Rio de Janeiro (AMRJ) to be fully operational by 2020. The ship displaces 21,578 tonnes, is 203.43 meters (667.4 ft) long and has a range of 8,000 nautical miles (15,000 km; 9,200 mi).
Before leaving HMNB Devonport for her new homeport in Rio's AMRJ, Atlântico underwent operational sea training under the Royal Navy's Flag Officer Sea Training (FOST) program.
On 12 November 2020, Atlântico was redesignated "NAM", for "multipurpose aircraft carrier" (Portuguese: Navio Aeródromo Multipropósito), from "PHM", for "multipurpose helicopter carrier" (Portuguese: Porta-Helicópteros Multipropósito), to reflect the ship's capability to operate with fixed-wing medium-altitude long-endurance unmanned aerial vehicles as well as crewed tiltrotor VTOL aircraft.

China: Current
2 STOBAR carriers:

Liaoning (60,900 tons) was originally built as the Soviet Kuznetsov-class carrier Varyag and was later purchased as a hulk in 1998 on the pretext of use as a floating casino, then towed to China for rebuild and completion. Liaoning was commissioned on 25 September 2012 and began service for testing and training. In November 2012, Liaoning launched and recovered Shenyang J-15 naval fighter aircraft for the first time. After a refit in January 2019, she was assigned to the North Sea Fleet, a change from her previous role as a training carrier.
Shandong (60,000–70,000 tons) was launched on 26 April 2017. She is the first to be built domestically, to an improved Kuznetsov-class design. Shandong started sea trials on 23 April 2018, and entered service in December 2019.
1 CATOBAR carrier:

Fujian (80,000 tons) is a CATOBAR carrier which was under construction between 2015 and 2016 before being completed in June 2022. She is being fitted out as of 2022 and will commence service in 2023–2024.
3 Landing helicopter docks

A Type 075 LHD, Hainan was commissioned on 23 April 2021 at the naval base in Sanya. A second ship, Guangxi, was commissioned on 26 December 2021 and a third ship, Anhui, was commissioned in October 2022.