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The term is now borne as a title mainly in Asia, Scandinavia, and the Middle East; but it may also be used generically to refer to the person or position of the heir apparent in other kingdoms. However, heirs apparent to non-imperial and non-royal monarchies (i.e., wherein the hereditary sovereign holds a title below that of king/queen, e.g., grand duke or prince), crown prince is not used as a title, although it is sometimes used as a synonym for heir apparent.
In Europe, where primogeniture governs succession to all monarchies except those of the Papacy and Andorra, the eldest son (Spain and the United Kingdom) or eldest child (Belgium, Denmark, the Netherlands, Norway, and Sweden) of the current monarch fills the role of crown prince or princess, depending upon whether females of the dynasty enjoy personal succession rights. The eldest living child of a monarch is sometimes not the heir apparent or crown prince, because that position can be held by a descendant of a deceased older child who, by "right of representation", inherits the same place in the line of succession that would be held by the ancestor if he or she were still living (e.g., Carl Gustaf, Duke of Jämtland, was de facto Crown Prince of Sweden from 1950 to 1973, as the senior grandson by male primogeniture of King Gustaf VI Adolf of Sweden, although the former Prince Sigvard, Duke of Uppland, was Gustaf VI's eldest living son, and Prince Bertil, Duke of Halland, his eldest living dynastic son during those years).
In some monarchies, those of the Middle East for example, in which primogeniture is not the decisive factor in dynastic succession, a person may not possess the title or status of crown prince by right of birth, but may obtain (and lose) it as a result of an official designation made on some other legal or traditional basis, e.g., former Crown Prince Hassan bin Talal of Jordan.
Compare heir apparent and heir presumptive. In Scandinavian kingdoms, the heir presumptive to the crown holds a different title than the heir apparent; Hereditary Prince (German: Erbprinz, French: prince héréditaire). That is also the title borne by the heirs apparent of Luxembourg and Liechtenstein, and by the heir or heiress presumptive of Monaco. In the Germanic monarchies abolished in 1918, hereditary prince, rather than crown prince, was also the title borne by the heirs apparent of the kingdoms of Bavaria, Hanover, Saxony and Württemberg, as well as those of grand duchies, of sovereign duchies and principalities, and of mediatized princely families.
Christian/Western traditional titles 
Many monarchies use or did use unique titles for their heirs apparent, often of historical origin:
- Dauphin (Kingdom of France), lit. [count of] Dauphiné
- Prince Royal (France in 1789–91 and the July Monarchy) & Prince Royal of Portugal and the Algarves (Portugal since 1815)
- Diadoch (Kingdom of Greece), lit. successor (see also below)
- Prince Imperial (Empire of Brazil, Second French Empire, and Empire of Mexico)
- Rex iunior (Kingdom of Hungary), junior king as he was crowned during the life of the incumbent
- Tsesarevich (Russia)
- Duke of Cornwall (England & the UK), automatically bestowed
- Duke of Rothesay (Scotland), automatically bestowed & currently used by the prince in place of his Welsh title when in Scotland
- Prince of Asturias (Castile & Spain)
- Prince of Gerona (Aragon & Spain)
- Prince of Viana (Navarre & Spain)
- Moravian Margrave in former Czech Kingdom
Some monarchies have used (although not always de jure) a territorial title for heirs apparent which, though often perceived as a crown princely title, is not automatically hereditary. It generally requires a specific conferral by the sovereign, which may be withheld.
Current and past titles in this category include:
- Caesar or Kaisar (Roman & early Byzantine Empires), lit. hairy but honoring Gaius Julius, distinguished from the senior Augustus
- Symbasileus (late Byzantine Empire), lit. co-emperor but still distinguished from the senior who was addressed as Autocrator
- Aetheling (Anglo-Saxon England) & edling (Welsh kingdoms), lit. of the royal family
- Duke of Brabant (Kingdom of Belgium); does not automatically descend by primogeniture, e.g., never held by Albert, Prince of Liège after his childless brother became king
- Duke of Estonia and Laland (Denmark; during, at least, reigns of Christopher II and Valdemar IV)
- Prince of Norway (Denmark-Norway); in 15th-19th centuries
- Prince of Orange (Netherlands)
- Prince of Wales (England, Great Britain, United Kingdom)
- King of the Romans (Holy Roman Empire) - an elective, rather than an inherited title, for the designated successor - usually the son, but sometimes the brother - of the Emperor
- Prince of Grão-Para (title of the eldest son of the Brazilian heir)
- King of Rome (First French Empire)
- Duke of Sparta, Kingdom of Greece; used briefly, within Greece, only by Prince Constantine, during reign of his father King George I
- Prince of Piedmont (title of the eldest son of the King of Sardinia, and then of the King of Italy, when it was alternated with Prince of Naples)
- Prince of Brazil (title of the Portuguese heir from 1645 to 1815)
- Prince of Beira (title of the eldest son of the Portuguese heir)
- Duke of Scania (Sweden during the time when Magnus IV of Sweden also was King of Terra Scania)
- Prince of Ani (Kingdom of West Armenia)
- Prince of Turnovo (Kingdom of Bulgaria)
- Prince of Alba Julia (Kingdom of Romania)
- Grand Voivode of Grahovo (Kingdom of Montenegro)
- Prince of Venice (see Prince Eugène de Beauharnais); for the heir presumptive to Napoleon I in his Kingdom of Italy
- Duke of Calabria (Kingdom of the Two Sicilies)
Crown prince in Arabia 
- Abdullah bin Abdulaziz Al Saud (In June 1982, when Fahd bin Abdulaziz became King, Prince Abdullah became Crown Prince the same day. He also maintained his position as head of the National Guard).
- Sultan bin Abdulaziz, Sultan bin Abdulaziz Al Saud (30 December 1930 – 22 October 2011), called Sultan al-Khair (Arabic: سلطان الخير, Sultan of good) was the Crown Prince of Saudi Arabia, from 2005 to 2011.
- Sheikh Nawaf Al-Ahmad Al-Jaber Al-Sabah (Arabic: الشيخ نواف الأحمد الجابر الصباح) is the Crown Prince of the State of Kuwait.
Other specific traditions 
- In Egypt, Prince of the Sa'id, meaning Prince of Upper Egypt
- In Persia, Qajar dynasty, the full style was Vala Hazrat-i-Humayun Vali Ahad, Shahzada (given name) Mirza, i.e. His August Imperial Highness the Heir Apparent, Prince ...;
- the above component vali ahad meaning 'successor by virtue of a covenant' (or various forms and etymological derivations) was adopted by many oriental monarchies, even some non-Muslim, e.g. Walet as alternative title for the Nepali (Hindu) royal heir apparent; first used Crown Prince Trailokya in the middle of the nineteenth century, taken from the Mughal title 'Vali Ahad'
Hindu tradition (Indian subcontinent):
- Yuvaraja was part of the full title in many princely states of India, e.g.
- in Jammu & Kashmir, the heir apparent was styled Maharaj Kumar Shri Yuvaraj (personal name) Singhji Bahadur
- Nepal, where the King was styled Maharajadhiraja:
- the heir apparent was styled: Sri Sri Sri Sri Sri Yuvarajadhiraj ('Young King of Kings', i.e. Crown Prince) (personal name) Bir Bikram Shah Deva;
- the eldest son of the heir apparent was styled: Sri Sri Sri Sri Sri Nava Yuvaraj ('Young Crown Prince') (personal name) Bir Bikram Shah Deva
East Asian traditions:
- The cognates of Chinese Huang Taizi (皇太子, "Great Imperial Son"): Japanese Kōtaishi, Korean Hwangtaeja (황태자), Vietnamese Hoàng Thái Tử -- if a son of the reigning emperor. In case the heir is a grandson, the title Huang Taisun (皇太孫), Kōtaison, Hwangtaeson (황태손), and Hoàng Thái Tôn, literally "Great Imperial Grandson", are used
- During the Joseon Dynasty in Korea, the crown prince was referred as Dong-gung(동궁, 東宮) due to the location of his residence from the main palace; or wangseja (王世子 왕세자). He was not necessarily the first-born son, wonja (元子 원자).
Southeast Asian traditions:
- Siam Makutrajakuman (สยามมกุฎราชกุมาร) in Thailand since 1886.
- Krom Phrarajawangboworn Sathanmongkol or Phra Maha Uparaja or commonly called Wang Na (or Front Palace) in Thailand prior to 1886.
- Kanjeng Gusti Pangeran Adipati Anom in Yogyakarta sultanate and Surakarta, Indonesia.
- Raja Muda or Tengku Mahkota in the Malay sultanates of Malaysia.
- Pengiran Muda Mahkota in Brunei
Equivalents in other cultures:
See also 
- Caesar (title) (since the tetrarchy) and Consors imperii
- Princeps iuventutis
- Prince of the blood
- "Crown Prince Party" of the People's Republic of China
- List of heirs apparent