hard rock is a loosely defined genre of rock music which has its earliest roots in mid-1960s garage, blues rock and psychedelic rock. It is typified by a heavy use of distorted electric guitars, bass guitar, drums, pianos, and keyboards.
One of the major influences of hard rock is blues music. American and British rock bands began to modify rock and roll, adding to the standard genre harder sounds, heavier guitar riffs, bombastic drumming and louder vocals. This sound created the basis for hard rock. Early forms of hard rock can be heard in the songs "You Really Got Me" by The Kinks (1964), "My Generation" by The Who (1965), "Helter Skelter" by The Beatles (1968), and "I Feel Free" by Cream (1966).
Hard rock emerged with groups of the late-1960s, such as The Who, Deep Purple, Iron Butterfly, Blue Cheer and Led Zeppelin who mixed the music of early rock bands with a more hard-edged form of blues rock and acid rock. Deep Purple helped pioneer the hard rock genre with the albums Shades of Deep Purple (1968), The Book of Taliesyn (1968), and Deep Purple (1969), but they made their big break with their fourth and distinctively heavier album, In Rock (1970). Led Zeppelin's eponymous first album, Led Zeppelin (1969), and The Who's Live at Leeds (1970), are examples of music from the beginning of the hard rock genre. The blues origins of the albums are clear, and a few songs by well-known blues artists are adapted or covered within them.
Led Zeppelin II (1969), Led Zeppelin's second album, was a watershed moment for the identity of hard rock, proving more popular than their third album Led Zeppelin III (1970). While the heavy aspects of their music remained, Led Zeppelin III was more folk rock-oriented than their second. 1971 saw [The Who release their highly-acclaimed album Who's Next.
Black Sabbath's first two albums, both released in 1970, are considered as important as any in launching hard rock into the mainstream.
Deep Purple's transformation of hard rock continued in 1972 with their album Machine Head, considered one of the first heavy metal albums, although some band members shunned that label. Two songs from Machine Head had great success: "Highway Star" and "Smoke on the Water." The latter song's main riff made it, for many, the "signature" Deep Purple song. Nazareth, a band out of Scotland, provided a blend of hard rock which commercialised the genre further with their best selling album, Hair of the Dog, which in turn, influenced numerous other bands. Free released their signature song "All Right Now", which has received massive radio airplay in both the UK and US.
In 1979, the differences between the hard rock movement and the rising heavy metal movement were highlighted when the Australian hard rock band, AC/DC, released its second-biggest album, Highway to Hell. AC/DC's music was based mostly on rhythm & blues and early-1970s hard rock, with the group explicitly repudiating the "heavy metal" tag.
The late 1980s saw the most commercially successful time period for hard rock. At this time it was the most reliable form of commercial popular music in the United States. Numerous hard rock acts achieved hits in the mainstream charts. One of those hits was the album Slippery When Wet (1986) by Bon Jovi, which spent a total of 8 weeks at the top of the Billboard 200 album chart, sold 12 million copies, and became the first hard rock album to spawn three top 10 singlesâtwo of which reached #1. In addition, the anthem rock album The Final Countdown by Swedish group Europe was released in 1986. It reached #8 on the U.S. charts, while hitting the top 10 in several other countries.