Slipknot is an American heavy metal band from Des Moines, Iowa. The band was formed in 1992 by percussionist Shawn Crahan, drummer Joey Jordison and bassist Paul Gray. After several lineup changes in its early years, the band settled on nine members for more than a decade: Corey Taylor, Mick Thomson, Jim Root, Paul Gray, Craig Jones, Sid Wilson, Shawn Crahan, Chris Fehn and Joey Jordison. Gray died on May 24, 2010, and was replaced during 2011-2014 by guitarist Donnie Steele.
All Hope Is Gone, third hiatus and Gray's death (2008-2010)
Preparation for Slipknot's fourth album began towards the end of 2007; work began at Sound Farm Studio in Jamaica, Iowa, with producer Dave Fortman in February 2008. The album was finished in June, and the band the All Hope Is Gone World Tour on July 9, 2008. Slipknot's fourth album, All Hope Is Gone, was released on August 20, 2008, debuting at number one on the Billboard albums chart. The album produced five singles; "All Hope Is Gone", "Psychosocial", "Dead Memories", "Sulfur" and "Snuff". 2009 marked the 10th anniversary of Slipknot's debut album; to commemorate the event, the band released a special edition version of Slipknot on September 9, 2009. The band toured in support of the album throughout 2008 and continued until October 31, 2009, resulting in Slipknot's third hiatus.  During the hiatus, several band members focused on respective side projects; Taylor founded Junk Beer Kidnap Band and returned to Stone Sour with guitarist Root; Crahan continued working with his band Dirty Little Rabbits; and drummer Jordison returned with his band Murderdolls and became the new permanent drummer of Rob Zombie. Percussionist Fehn is now a full-time bassist with metalcore band Will Haven and Sid Wilson founded the eponymous band Sid.  In 2010, Gray was planning to tour with the supergroup, Hail!, but on May 24, 2010, he was found dead in an Urbandale, Iowa hotel room. Circumstances surrounding his death at the time were not immediately known; an autopsy suspected his death was not intentional but did not reveal the cause. The day after his death, the remaining eight members of the band held a live, unmasked, press conference alongside Gray's widow and brother. On June 21, the cause of death was confirmed as an accidental overdose of morphine and synthetic morphine substitute fentanyl.  The band was hesitant to comment on the future of Slipknot. The members made conflicting statements in interviews; drummer Jordison told The Pulse of Radio "there is another Slipknot record already kinda in the making". Vocalist Taylor told FMQB Productions' he was "very conflicted about whether or not [he wants] to do anything with Slipknot". The band released their fourth video album (sic)nesses on September 28, 2010; it debuted at number one on the Billboard Top Music Video Charts. The DVD features Slipknot's entire live performance at the 2009 Download Festival and a 45-minute film documenting their tour in support of All Hope Is Gone, and served as a tribute to Paul Gray.

Q: When was their third hiatus?
A: October 31, 2009, resulting in Slipknot's third hiatus.
Why did they take this hiatus?
several band members focused on respective side projects;
several band members focused on respective side projects;