The FIDE World Cup refers to three different events over the years. Since 2000, it has been a major chess event organized by Fide the International Chess Federation. Since 2005, it has been a 128-player single-elimination
In 2000 and 2002 FIDE, the International Chess Federation staged their "First Chess World Cup" and "Second Chess World Cup" respectively. These were major tournaments, but not directly linked to the World Chess Championship
Since 2005, a different event of the same name has been part of the World Chess Championship cycle. This event is held every two years. It is a 128-player knockout tournament, in the same style as the Tilburg tournament.
The event was held in 2005, 2007, 2009, and 2011 in Khanty-Mansiysk, and subsequently, FIDE has given preference to bids for the Olympiad that also contain a bid for the preceding World Cup. During the 2015 finals of the World Cup, the main organizer commented "We received the right to host the Olympiad, and then we were given an additional event – the World Cup."
The Chess World Cup 2005 qualified ten players for the Candidates Tournament Since then, every World Cup has qualified between one and three players for the Candidates Tournament.
Two World Cup qualifiers Boris Gelfand in 2009 and Sergey Karjakin in 2015 won the subsequent Candidate's tournament and played in the World Championship match, in 2012 and 2016
Format
Since 2005, the format has been 128 players with 7 single-elimination rounds of "mini-matches", 2 games each followed by a series of rapid then blitz tiebreaks if necessary. The final usually has 4 games before the tiebreaks start. Since 2015, an extra rest day has recently been added before the semi-finals, in addition to before the final.
Some criticism has been leveled at the scheduling effects, with the event being rather long (26 days), particularly with almost all of the players have left long before the end. Fatigue thus plays a critical role, and while some players seek to conserve energy by avoiding tiebreaks, others "agree" (either explicitly or implicitly) to make quick draws in the 2 long games and decide the winner in tiebreaks. It is often remarked that the system is primarily a lottery of who survives, though better players have more chances on the whole. The anticlimax of the 4-round final, with both players now already qualified for them, has also been criticized.
Winners
"Qual" refers to the number of players who qualify for the [Candidates Tournament] (marked with green background). For example, in 2015, the top 2 finishers qualified for the [2016 Candidates Tournament]