The Candidates Tournament is a chess tournament organized by the world chess federation FIDE since 1950, as the final contest to determine the challenger for the World Chess Championship. The winner of the Candidates earns the right to a match for the World Championship against the incumbent World Champion.

In the early history, it was contested as a triennial tournament, but after the split of the World Championship in the early 1990s, followed with the changes in the determination of the World Champion Challenger, the tournament is held only periodically.

The number of players in the tournament varied over the years, between eight and fifteen players. Most of these qualified from Interzonal tournaments, though some gained direct entry without having to play the Interzonal.

The first Interzonal/Candidates World Championship cycle began in 1948. Before 1965, the tournament was organized in a round-robin format. From 1965 on, the tournament was played as knockout matches, spread over several months. In 1995–1996, the defending FIDE champion (Anatoly Karpov) also entered the Candidates, in the semi-finals, so the winner was the FIDE world champion.

Shakhriyar Hamid oglu Mammadyarov (Azerbaijani: Şəhriyar Həmid oğlu Məmmədyarov) (born 12 April 1985 in Sumgayit, Azerbaijan SSR), also known for his Shah nickname, is a chess Grandmaster. On the September 2010 FIDE rating list he was ranked number nine in the world with an Elo rating of 2756.

Shakhriyar Mamedyarov was born April 12, 1985 in Sumgayit, Azerbaijan.

In 2003 he won the World Junior Chess Championship. He repeated his victory in 2005 (thus becoming the only two-time champion), achieving an incredible 2953 performance rating after eight rounds. This gained him an invitation to the Essent Tournament 2006 in Hoogeveen, and by winning this one and also the 2007 edition, Shakhriyar achieved world fame.

In 2005 Mamedyarov competed at European Club Cup and had the second highest performance rating (2913) among all of the participants (Vassily Ivanchuk had the highest).

IM Goran Antunac has commented that Mamedyarov is a true virtuoso at handling the pieces, always finding the best squares for them.

Peter Veniaminovich Svidler (Russian: Пётр Вениами́нович Сви́длер; Pyotr Veniaminovich Svidler, born June 17, 1976, in Leningrad) is a Russian chess grandmaster. He is six-time Russian champion (1994, 1995, 1997, 2003, 2008, 2011). He placed shared second (together with Viswanathan Anand) in the FIDE World Chess Championship 2005 with 8.5 points out of 14 games, finishing 1.5 points behind the winner, Veselin Topalov. In the World Chess Championship 2007, he placed 5th among the eight players. He has won five team gold medals and one individual bronze medal at Chess Olympiads.

Svidler learned to play chess when he was six years old. In 1992, he tied for 1st–2nd with Ragim Gasimov in the USSR Junior Open Chess Championship. He became Grandmaster in 1994.

In 2001, he reached the semi-finals of the FIDE World Championship. Andrei Lukin is his coach.

Svidler is a noted proponent of Fischer Random Chess (also called Chess960). He won the first edition of the Chess960 Open held in Mainz, Germany. At the 2003 Mainz Chess Classic, he became Chess960 World Champion by beating Péter Lékó in an eight-game match. He successfully defended his title twice, defeating Levon Aronian in 2004 and Zoltán Almási in 2005, before losing it to Aronian in 2006.

Sven Magnus Øen Carlsen (born 30 November 1990) is a Norwegian chess Grandmaster and chess prodigy who is currently the number-one ranked player in the world. In January 2010 he became the seventh player in history to be ranked number one in the world on the official FIDE rating list. His peak rating is 2835, the second highest in history, after Garry Kasparov.

On 26 April 2004 Carlsen became a Grandmaster at the age of &1000000000000001300000013 years, &10000000000000148000000148 days, making him the third-youngest Grandmaster in history. On 1 January 2010 the new FIDE rating list was published, and at the age of &1000000000000001900000019 years, &1000000000000003200000032 days, he became the youngest chess player in history to be ranked world number one, breaking the record previously held by Vladimir Kramnik. Carlsen was also the 2009 World blitz chess champion.

His performance at the September–October 2009 Nanjing Pearl Spring tournament has been described as one of the greatest in history and lifted him to an Elo rating of 2801, making him the fifth player to achieve a rating over 2800 – and aged 18 years 10 months at the time, by far the youngest to do so.