System of a Down use a wide range of instruments, including baritone electric guitars, electric mandolins, sitars, 12-string classical guitars and many other East Asian instruments. Their main influence is noticeably the veteran heavy metal bands Black Sabbath and Slayer, but they also draw on punk rock, jazz, fusion, Armenian folk music, classic rock, blues, and industrial metal.

The band enjoyed moderate success with their first singles, "Sugar" and "Spiders", from their debut album System of a Down. However, their big break came from their critically acclaimed second album, Toxicity, which debuted at #1 on the American and Canadian charts, eventually going multi-platinum. The album was #1 in America on the week of the September 11, 2001 attacks. Their first big hit was the controversial "Chop Suey!", released in the late summer of 2001. System of a Down received constant airplay in the United States throughout late 2001 and 2002 with their hits, "Chop Suey!", "Toxicity", "Aerials", off their second album, Toxicity, and "Innervision" off their third album, Steal This Album!.

Their third album, containing songs from the Toxicity and System of a Down recording sessions, was abruptly released as Steal This Album!, weeks after early recordings of most of the songs had leaked out onto the internet. There are five different designs of the album available. One version of the CD resembles a CD Recordable that was labeled with a felt-tip marker, and the other four featured designs by individual band members.

In 2004, the band recorded two brand new albums for release in 2005 that are being released approximately 4 to 6 months apart from each other. They are Mezmerize and Hypnotize. Mezmerize was released in the United States, UK and Europe on May 17 2005, and was released in Australia on May 22 2005, while Hypnotize will be released approximately four to six months after. The dates and order of release for these two albums were somewhat controversial among fans and fan sites in early 2005, as some believed that the release was to be in the opposite order and the first one was to come out in April. In early January, 2005, a new track called "Cigaro" was purposefully leaked onto the internet to praise from fans, followed by the release of the single "BYOB"(Bring Your Own Bombs), which is working its way up the North American singles charts. Mezmerize immediately shot up to the top of the US charts, making it the group's second consecutive number-one debut. First week sales rocketed to over 800,000 copies worldwide, with the album debuting at #1 in over a dozen other countries, including Canada, Japan, Australia, Germany, and France. Initial critic reviews have been overwhelmingly favorable.

--Wikipedia