Searing guitars, spit flying, drums that pummel and shrieks of melody, man-made noises that chill the blood and eyes that glare. The heat is thick, the air heavy and moist, yet the energy keeps flowing between the audience and the band -- a cycle you can almost touch if you could keep your hands from shaking and your body from losing complete control.

The word rock brings extended guitar solos, tattoos, emphatic beats, piercing, dense bass-and-drum sound, vigorous vocals, adrenaline, loud distorted guitars, intensity and overall loudness to ones' mind. This music genre entered the mainstream sometime in the 60s. The most famous sub-genres of rock music are hard rock and heavy metal that developed in the late '60s and early 70s. Heavy metal attracted a worldwide fan following known as 'metalheads' or 'headbangers'. Though overwhelmingly disliked by music critics, bands such as Metallica and Iron Maiden continued the popularity of the style.

According to Allmusic.com, rock in its purest form has three chords, a strong, insistent back beat, and a catchy melody. Some rockers have expanded this definition, while others completely exploded the constrictions of the genre.

Rockers of the early days were known as hard-drinking and hard-living characters. This, most probably, was the reason why rock and roll lifestyle was associated with sex and drugs, thereby coining the term Sex, Drugs and Rock & Roll. Hard rock is a breed with less syncopation, less blues, more showmanship and more brute force, according to a famous music critic for The New York Times.

Below are some of my favourite rock bands covering various sub-genres:

Founded as Xero by three high school friends including Mike Shinoda, the band changed its name to Linkin Park shortly after it recruited Chester Bennington as lead vocalist to replace Mark Wakefield who left the band for other projects. With Bennington's screaming vocals, the Agoura Hills, Calif., band released their debut album, Hybrid Theory, also one of the band's former names. The Recording Industry Association of America labeled the album Diamond. The band then released Meteora, which topped the Billboard 200's album charts, a clear sign of the band's continued success. All in all, Linkin Park has sold more than 50 million albums.

Linkin Park adopted many sub-genres of rock including alternative metal, nu-metal and rap rock. Apart from topping Jasir's List of Best Rock Bands, the band has won two Grammy Awards, each for Best Rap/Sung Collaboration and Best Hard Rock Performance. The band sang the OST for Transformers 1 and 2.

Bennington has the 46th spot in Hit Parader's list of Heavy Metal's All-Time Top 100 Vocalists, two notches below Marilyn Manson who has the 44th spot. Shinoda has been placed at number 72.

After jumping from one name to the other, the Bakersfield, Calif., band finally settled at Korn that was suggested by new lead vocalist Jonathan Davis. He wrote their logo with a crayon in a child's handwriting, with a 'K' and a backwards upper-case 'R'.

The band released their eponymous debut album in October 1994. All the songs of their first album, Blind, got a decent amount of airplay and attention. But it was Follow the Leader that gave the band its breakthrough. The album was a huge success, debuting at #1 on Billboard. The album exposed the band to a wider, mainstream audience.

"We have always just been a band that rocks. We didn't like when people called us a metal band, we are just Korn," Davis commented on the band's music style in the 'Korn - Freaks Alive' DVD. The band has sold more than 30 million albums worldwide. The band has also won two Grammy awards, of six nominations.

Davis ranks 16th on Hit Paraders list of Heavy Metal's All-Time Top 100 Vocalists.

Slipknot has done everything they can to earn the place they have achieved. Their fans are affectionately known as the Maggots. Each member of the band wears matching jumpsuit uniforms and has a unique mask and their appearance has been a subject of much criticism. The name Slipknot was suggested by current drummer Joey Jordison, who also designed the 'S' logo. The band recruited current vocalist Corey Taylor from Stone Sour and released its self-titled debut album in 1999. The album was certified Platinum, creating a huge fan base. The band's musical direction is influenced by death metal, black metal, heavy metal, as well as nu-metal.

There has been controversy over Slipknot's lyrics, including a case in which two young killers blamed the lyrics from the song Disasterpiece for their vicious crime in which they stabbed a young man 20 times and then slit his throat.

Frontman Taylor ranks #86 in Hit Parader's list of Heavy Metal's All-Time Top 100 Vocalists.

Dark and twisted -- that's how some describe the Chicago based metal band Disturbed. Known as Brawl in its early days, the band changed its name to Disturbed soon after it hired vocalist David Draiman. In an interview Draiman said he had suggested the name Disturbed because he had been contemplating this name for a band for years.

Disturbed's debut album, The Sickness launched the band into stardom. The album peaked at #29 on the Billboard 200 and has sold more than 4 million copies in the US since its release. Though classified by most as a rock or nu-metal band, Disturbed is also regarded as alternative rock, alternative metal, heavy metal and rap metal by some music critics.

Draiman said in the band's home documentary 'M.O.L.' that the lyrics he writes are inspired by life experiences and perceptions. He also said that he likes to present his ideas with cryptic lyrics.