Heavy metal (or simply metal) is a genre of rock music that developed in the late 1960s and early 1970s, largely in the United Kingdom. With roots in blues rock and psychedelic/acid rock, the bands that created heavy metal developed a thick, massive sound, characterized by highly amplified distortion, extended guitar solos, emphatic beats, and overall loudness. Heavy metal lyrics and performance styles are sometimes associated with aggression and machismo. 

In 1968, the first heavy metal bands such as Led Zeppelin, Black Sabbath and Deep Purple attracted large audiences, though they were often derided by critics. During the mid-1970s, Judas Priest helped spur the genre's evolution by discarding much of its blues influence; Motörhead introduced a punk rock sensibility and an increasing emphasis on speed. Beginning in the late 1970s, bands in the new wave of British heavy metal such as Iron Maiden and Saxon followed in a similar vein. Before the end of the decade, heavy metal fans became known as "metalheads" or "headbangers". 

During the 1980s, glam metal became popular with groups such as Mötley Crüe and Poison. Underground scenes produced an array of more aggressive styles: thrash metal broke into the mainstream with bands such as Metallica, Megadeth, Slayer, and Anthrax, while other extreme subgenres of metal such as death metal and black metal remain subcultural phenomena. Since the mid-1990s popular styles have further expanded the definition of the genre. These include groove metal (with bands such as Pantera, Sepultura, and Lamb of God) and nu metal (with bands such as Korn, Slipknot, and Linkin Park), the latter of which often incorporates elements of grunge and hip hop.
When did heavy metal develop?
Is it sometimes just called metal?
Where did it originate?
What are the lyrics associated with?
anything else?
In 1968, what was a popular band?
Who else?
And who else?
Did they perform for small groups?
What did Judas Priest move away from, which genre?
What did Motorhead add?
Did it change the tempo, too?
At the end of the 70's what were the fans called?
or?
Which group became popular in  the 80s?
and?
Who is a thrash metal band?
in the late 1960s and early 1970s,
Heavy metal (or simply metal) is a genre of rock music that developed in the late 1960s and early 1970s,
yes
Heavy metal (or simply metal)
in the United Kingdom.
 largely in the United Kingdom.
aggression
Heavy metal lyrics and performance styles are sometimes associated with aggression and machismo
and machismo
 and machismo
Led Zeppelin
In 1968, the first heavy metal bands such as Led Zeppelin
Black Sabbath
In 1968, the first heavy metal bands such as Led Zeppelin, Black Sabbath and Deep Purple attracted large audiences
Deep Purple
and Deep Purple attracted large audiences
No
 attracted large audiences,
its blues influence;
udas Priest helped spur the genre's evolution by discarding much of its blues influence;
punk rock sensibility
Motörhead introduced a punk rock sensibility
yes
nd an increasing emphasis on speed.
metalheads
heavy metal fans became known as "metalheads"
headbangers
 or "headbangers". 
Mötley Crüe
During the 1980s, glam metal became popular with groups such as Mötley Crüe
Poison
and Poison
Metallica,
thrash metal broke into the mainstream with bands such as Metallica, 