Name: Neant Alioum
League he works in: Cameroonian MTN Elite One
Bottom line: One of Africa's most respected officials, he has taken charge of a number of high-profile matches within the continent. Officiated at last year's U-20 World Cup and FIFA Club World Cup.
Name: Daniel Frazer Bennett
Country: South Africa
League he works in: South African Premier League
Bottom line: Not afraid to award penalties and has brandished three red cards in his last four internationals.
Name: Noumandiez Desire Doue
Country: Ivory Coast
League he works in: Ivorian Ligue 1
Bottom line: Named African Referee of the Year in 2011 and is the oldest official at the 2014 World Cup at age 44.
Name: Bakary Gassama
League he works in: Gambian Premier League
Bottom line: Considered one of the best up-and-coming officials in African football. He is unlikely to make any rash decisions.
Name: Djamel Haimoudi
League he works in: Algerian Championnat National de Premiere Division
Bottom line: Named African Referee of the Year in 2012 and 2013. Officiated the 2013 African Nations Cup final and the 2013 Confederations Cup third-place playoff. No-nonsense approach.
Name: Alireza Faghani
League he works in: Iranian Pro League
Bottom line: Lenient. He has shown just 31 yellows and no reds in his past nine internationals. His father was also a referee.
Name: Ravshan Irmatov
League he works in: Uzbek League
Bottom line: Considered one of the world's leading referees. He officiated five games at the 2010 World Cup, including the prestigious opening match and semifinal. However, he was widely criticised for awarding a goal to Italy after he had blown the whistle for a foul in a 2013 Confederations Cup match against Brazil.
Name: Yuichi Nishimura
League he works in: Japanese J-League
Bottom line: Named Asian Referee of the Year in 2012. He is not afraid to show a red card, and sent off Uruguay's Nicolas Lodeiro and Brazil's Felipe Melo at the 2010 World Cup.
Name: Nawaf Abdulla Ghayyath Shukralla
League he works in: Saudi Professional League
Bottom line: Whistle-happy. Frequently seen delving into his pocket to brandish a card. Has dished out six red cards in his last 15 internationals.
Name: Benjamin Jon Williams
League he works in: Australian A-League
Bottom line: Named Asian Referee of the Year in 2013. Some of his decisions have made him very unpopular among Australian football audiences this season, such as his handling of Melbourne Heart's 2-2 draw with Wellington Phoenix.
Name: Felix Brych
League he works in: German Bundesliga
Bottom line: While he is one of Europe's leading referees, he does have a propensity for making controversial decisions. He was heavily criticised for awarding this phantom goal in Bayer Leverkusen's win over Hoffenheim in October 2013. Officiated the 2014 Europa League final.
Name: Cuneyt Cakir
League he works in: Turkish Super Lig
Bottom line: Very strict and meticulous. He faced the wrath of Sir Alex Ferguson after awarding Nani a debatable red card in Manchester United's Champions League defeat to Real Madrid in March 2013.
Name: Jonas Eriksson
League he works in: Swedish Allsvenskan
Bottom line: Likes to let the game flow and has a tendency not to award cards -- he has issued just three reds in his last 16 internationals. He is a millionaire but continues refereeing because he loves the game.
Name: Bjorn Kuipers
League he works in: Dutch Eredivisie
Bottom line: One of the best in the business. He can be seen as a bit fussy at times but his solid officiating of the 2013 Confederations Cup final and 2014 UEFA Champions League final means he could well be awarded the big one this summer.
Name: Milorad Mazic
League he works in: Serbian SuperLiga
Bottom line: Keeps a cool head under pressure and refereed a number of high-profile UEFA Europa League and Champions League matches this season.
Name: Svein Oddvar Moen
League he works in: Norwegian Tippeligaen
Bottom line: Lenient. He has a tendency not to award cards (just 21 yellows and one red in his last 10 internationals), and is relatively inexperienced on the elite stage. He is also an ambulance driver.
Name: Pedro Proenca
League he works in: Portuguese Primeira Liga
Bottom line: Voted IFFHS World Referee of the Year in 2012. An eagle-eyed, experienced referee who is very communicative on the pitch. He officiated the 2012 UEFA Champions League and UEFA European Championship finals.
Name: Nicola Rizzoli
League he works in: Italian Serie A
Bottom line: Like famous Italian referee Pierluigi Collina, Rizzoli is one of the most respected officials and great assessors of the game. He has taken charge of a number of high-profile games -- including the 2013 UEFA Champions League final -- and is renowned for his ability to make bold but often correct decisions.
Name: Carlos Velasco Carballo
League he works in: Spanish La Liga
Bottom line: One of the game's most experienced officials. He is not afraid to brandish cards -- issuing 51 yellows and three reds in his last eight La Liga matches.
Name: Howard Webb
League he works in: English Premier League
Bottom line: Voted IFFHS World Referee of the Year in 2010 and officiated both the UEFA Champions League and FIFA World Cup final that year. He is renowned for his authoritative yet calm approach, though the 2013-14 season was not one of his finest.
Name: Joel Antonio Aguilar Chicas
Country: El Salvador
League he works in: Salvadoran Primera Division
Bottom line: Officiated at the 2010 FIFA World Cup and the 2013 Confederations Cup. Likes to let the game flow. Controversially allowed the 2014 World Cup qualifier between USA and Costa Rica go ahead despite a blizzard.
Name: Mark Geiger
Country: United States
League he works in: American Major League Soccer
Bottom line: He will be the first MLS ref at a World Cup since 2002. He is not afraid to make big decisions and is considered ruthless.
Name: Walter Lopez
League he works in: Guatemala Liga Nacional
Bottom line: Strict. Not afraid to brandish his cards -- distributing 81 yellows and six reds in his last 12 domestic matches.
Name: Roberto Moreno Salazar
League he works in: Panamanian League
Bottom line: Missed out on the final cut for the 2010 World Cup. He is very experienced and has taken charge of a number of high-profile CONCACAF matches.
Name: Marco Antonio Rodriguez Moreno
League he works in: Mexican Liga MX
Bottom line: Refereed at the 2006 and 2010 World Cups and was voted CONCACAF Referee of the Year in 2013. Nicknamed "Dracula," he likes to be at the centre of attention and is unforgiving in his decisions. Was banned for five matches for issuing double yellow cards in a game between Tigres and Santos Laguna.
Name: Norbert Hauata
League he works in: Oceania Champions League
Bottom line: Lenient -- he has shown 23 yellows and zero reds in his last nine internationals. Officiated at the U-17 World Cup last year.
Name: Peter O'Leary
Country: New Zealand
League he works in: Australian A-League
Bottom line: An easygoing referee who is reluctant to dish out cards -- he has not sent a player off in his previous 11 internationals. He was once invited to attend an English Premier League match as a guest of referee Steve Bennett and was asked to become the fourth official after an assistant referee picked up an injury.
Name: Victor Hugo Carrillo Casanova
League he works in: Peruvian Primera Division
Bottom line: Officiated at the U-20 World Cup last year. Does not hesitate to point to the spot, and sent off seven players in 10 domestic games between February and May 2014.
Name: Enrique Osses
League he works in: Chilean Primera Division
Bottom line: Controversial. He has a propensity to flash cards and distributed 89 yellows, 12 reds and six penalties during a 15-game spell in 2013. He has been accused in his homeland of favouring Universidad de Chile and was once banned after failing to send off a player despite showing him two yellow cards. Was also punched by Union Espanola goalkeeper Ignacio Gonzalez in 2005, resulting in a 22-game ban for the player.
Name: Nestor Pitana
League he works in: Argentine Primera Division
Bottom line: Widely recognised as the best referee in South America for his ability to read the game well and make correct decisions under pressure.
Name: Sandro Ricci
League he works in: Brazilian Campeonato Serie A
Bottom line: Officiated the 2013 FIFA Club World Cup final. Doesn't always allow the game to flow.
Name: Wilmar Alexander Roldan Perez
League he works in: Colombian Categoría Primera A
Bottom line: Regarded as one of the best young and up-and-coming referees. He took charge at the London 2012 Olympics and the U-20 World Cup last year.
Name: Carlos Alfredo Vera Rodriguez
League he works in: Ecuadorian Serie A
Bottom line: Has a tendency to award soft penalties and is no stranger to brandishing a red card, having sent off four players in his last six internationals.