Question: Dave Grohl and Brent Hinds are both what type of artist?
Context: Foo Fighters is the self-titled debut studio album by American hard rock band Foo Fighters, released on July 4, 1995, by Capitol Records through Dave Grohl's label Roswell.  Grohl wrote and recorded the entire album himself – with the exception of a guest guitar spot by Greg Dulli – with the assistance of producer Barrett Jones at Robert Lang Studios in Seattle, Washington, in 1994.  Grohl claimed he recorded the album just for fun, describing it as a cathartic experience to recover from the death of his Nirvana lead singer Kurt Cobain. Premier Guitar is an American multimedia guitar company devoted to guitarists.  Founded in 2007, it is based in Marion, Iowa, and has an editorial staff composed of experienced musicians.  Content includes instructional material, guitar gear reviews, and guitar news.  Interviews have included guitarists such as Pete Townshend of The Who, Ron Wood of the Rolling Stones, Joe Perry of Aerosmith, Guthrie Govan, Brent Hinds and Bill Kelliher of Mastodon, and Dave Mustaine and Chris Broderick of Megadeth.  The magazine is published online for free, and includes multimedia such as instructional videos and podcasts.  The magazine also has a free weekly newsletter and an online "Gear Search" service, where guitarists can search for, buy, and sell guitar equipment.  As of March 2012, the magazine's print and multimedia platforms combined served 1.5 million unique readers per month, making it the most read magazine on this topic worldwide. Sonic Highways is a 2014 American documentary miniseries directed by Dave Grohl and written by Mark Monroe.  The documentary was made concurrently with Foo Fighters' eighth album, "Sonic Highways", and was broadcast on HBO.  Grohl described the project as "a love letter to the history of American music".  Each of the eight episodes is presented as an exploration of the musical history of a different American city through a series of interviews by Grohl.  The group is also shown incorporating what they learned from the interviews into the writing and recording of a new song in or near that city.  The series debuted on October 17, 2014. "Mantra" is a song by Dave Grohl, Josh Homme, and Trent Reznor from the 2013 album "", the soundtrack to the 2013 documentary "Sound City".  Grohl was joined by different artists for different tracks as Grohl's Sound City Players.  For "Mantra", the final track on the album, he was joined by Homme and Reznor.  Homme also appeared on two other tracks on the album, "Centipede" and "A Trick With No Sleeve". David Eric Grohl (born January 14, 1969) is an American rock musician, guitarist, singer, drummer, songwriter, record producer, and film director.  He is the former drummer of the grunge band Nirvana and the frontman and founder of the rock band Foo Fighters, of which he is the lead vocalist, rhythm and lead guitarist, and primary songwriter. Probot was a heavy metal side project of ex-Nirvana drummer and Foo Fighters rhythm guitarist and lead-singer Dave Grohl.  Described by Grohl as "a death metal "Supernatural,"" the album mixes instrumentals recorded by Grohl himself with various metal singers whom the musician admired.  The album was released in February 2004 by Southern Lord Records.  It featured one single entitled "Centuries of Sin"/"The Emerald Law". Wasting Light is the seventh studio album by American rock band Foo Fighters.  It was released on April 12, 2011 on RCA Records, and is the first album to feature rhythm guitarist Pat Smear since "The Colour and the Shape" (1997), making the band a five piece with the album.  Wishing to capture the essence of the group's earlier work and avoid the artificiality of digital recording, frontman Dave Grohl arranged for the band to record in his garage in Encino, California using only analog equipment.  The sessions were supervised by producer Butch Vig, with whom Grohl had worked on Nirvana's "Nevermind".  Since the old equipment did not allow for many mistakes to be corrected in post-production, the band spent three weeks rehearsing the songs, and Vig had to relearn outdated editing techniques.  The band went for a heavier and rawer sound to contrast with the musical experiments from their previous albums, and most of the lyrics were written as Grohl reflected upon his life and possible future.  Guest musicians include Bob Mould, Krist Novoselic, Jessy Greene, Rami Jaffe and Fee Waybill. Foo Fighters is an American alternative rock band formed by multi-instrumentalist and vocalist Dave Grohl in 1994.  After recording the album "Foo Fighters" alone, Grohl enlisted guitarist Pat Smear, bassist Nate Mendel and drummer William Goldsmith to join the band.  This lineup recorded the second Foo Fighters album, 1997's "The Colour and the Shape", although most of Goldsmith's drum recordings were removed and re-recorded by Grohl for the release, after he left the band due to creative tensions.  Goldsmith was replaced by Taylor Hawkins, and Franz Stahl replaced Smear after he also departed, although he only remained in the band for a short period and did not record an album with the group.  The group's third album, "There Is Nothing Left to Lose", featured Hawkins on drums and was released in 1999. Brent Hinds (born William Brent Hinds; January 16, 1974) is an American musician best known as a member of the Atlanta, Georgia metal band Mastodon, in which he shares guitar duties with Bill Kelliher and vocal duties with Troy Sanders and Brann Dailor. "These Days" is the third single, (fourth in the UK), from the American rock band Foo Fighters' seventh studio album "Wasting Light".  It was written by Dave Grohl and co-produced by Butch Vig.  Dave Grohl has stated that it is his favourite song that he has ever written.  On August 18, 2012, the Foo Fighters performed "These Days" at Pukkelpop, as a tribute to the people who died or were injured there a year earlier, due to a violent thunderstorm that raged over the festival grounds.
Answer: musician