23 aircraft carriers sail the waters of the world. From the USA to France, here are the flag states

As for the second question, no one is able to challenge the primacy of the United States. In fact, the US Navy has 11 large nuclear-powered Catobar aircraft carriers, each of which can carry around 80 fighters. The most recent is the USS Gerald R. Ford. Aircraft carriers constitute the main US force in the Atlantic and Pacific oceans. They are the largest fleet in the world, with a total deck space that is twice that of all other states combined.

As far as China is concerned, the People's Liberation Army Navy is rapidly expanding its fleet with the aircraft carriers Liaoning, Shandong and the newer Fujian. Total for Beijing: three. The Russian Federation has (or rather had) the Admiral Kuznecov. The 67,000-tonne fully loaded flagship of the Russian fleet, capable of carrying some thirty Sukhoi Su-33s and Mig-29Ks as well as a few helicopters, launched in 1985, is still undergoing repairs, so much so that there have been rumours of its eventual decommissioning.

The Indian Navy has the INS Vikramaditya and the newer INS Vikrant. Notably, after years of delays, India's first domestically produced aircraft carrier, the 40,000-ton INS Vikrant, has arrived. The Vikrant is relatively small by modern aircraft carrier standards and uses a ski-launch ramp rather than catapults for aircraft take-off, limiting the types of aircraft the ship can carry and their performance. The ship has joined the Indian aircraft carrier INS Vikramaditya, a former Russian ship from the USSR period that has been modified, which also uses a launch ramp. However, observes Nick Child, Senior Researcher for Naval Forces and Maritime Security at the International Institute for Strategic Studies (IISS), it remains to be seen if and when the navy will be able to realise its plan to create a force of three aircraft carriers, including a larger and more powerful ship equipped with catapults.

The Japanese Navy (Japan Maritime Self Defence Forces) has decided to re-equip itself with aircraft carriers. These are helicopter carriers converted for F-35B fighters), the JS Izumo (DDH-183) and JS Kaga (DDH-184), both in service with the Japan Maritime Self Defence Force. These units have been retrofitted to accommodate STOVL aircraft, marking a strategic shift in the country's naval defence capabilities.

Then there is France: the Marine Nationale owns the FS Charles de Gaulle, the only non-US nuclear-powered aircraft carrier.

The British Royal Navy has two modern Queen Elizabeth class aircraft carriers (HMS Queen Elizabeth and HMS Prince of Wales).

The Italian Marina Militare has the aircraft carrier (or aircraft cruiser) Cavour (the ship Garibaldi is no longer in service).

Closing the list, Spain has no 'traditional' (vertical take-off/short take-off) aircraft carriers in active service, but operates amphibious assault ships such as the Juan Carlos I (L-61), which can embark vertical take-off (STOVL) aircraft such as the F-35B, acting as de facto light aircraft carrier-like platforms for air power projection, although they are classified differently.