Eddie Van Halen’s “Eruption” solo popularized the tapping style of guitar playing, and in doing so revolutionized the sound of rock. Not bad for a song that wasn't even intended to be released.

On Sept. 8, 1977, Van Halen were in the midst of working on their debut album.

“I showed up at the recording studio early one day and started to warm up because I had a gig on the weekend and I wanted to practice my solo guitar spot,” Eddie recalled during a 1996 interview with Guitar World.

The guitarist had been mixing his distinctive solo – which would become “Eruption” – into the Van Halen live show. Still, he’d never considered recording it for their album. As he rehearsed the instrumental piece in the studio, the sound garnered attention.

"Our producer, Ted Templeman, happened to walk by and he asked, 'What's that? Let's put it on tape!,'” the guitarist noted. “So I took one pass at it, and they put it on the record. I didn't even play it right. There's a mistake at the top end of it.”

Templeman thought so highly of “Eruption” that he put it second on the Van Halen track list, in between future hits "Runnin' with the Devil" and "You Really Got Me." Such placement would normally be unheard of for a solo instrumental track, but “Eruption” was different.

In just one minute and 42 seconds, Van Halen changed what a guitar solo could do. His revolutionary two-handed tapping technique produced sounds unlike what fans had ever heard before.

Listen to 'Eruption' From 'Van Halen'

“It’s like having a sixth finger on your left hand,” the guitarist once explained of the approach. “Instead of picking, you’re hitting a note on the fretboard.”

Van Halen had invented the technique unintentionally.

“I was just sittin’ in my room at the pad at home, drinkin’ a beer, and I remembered seeing people stretching one note and hitting the note once,” he explained to Classic Rock in 1978. “They popped the finger on there to hit one note. I said: well, fuck, nobody is really capitalizing on that.

“Nobody was really doing more than just one stretch and one note real quick. So I started dickin’ around, and said: fuck! This is a totally another technique that nobody really does. Which it is. I haven’t really seen anyone get into that as far as they could, because it is a totally different sound. A lot of people listen to that and they don’t even think it’s a guitar. ‘Is that a synthesizer? A piano? What is that?’”

Watch Eddie Van Halen Perform 'Eruption' in Concert

“Eruption” ushered in the sound of ‘80s rock. After Van Halen became a monumental success, every rocker wanted to sound like the world’s newest guitar god. Eddie later admitted he found the copycats to be “kind of funny.”

“With me, [the tapping technique] was a form of expression – part of my style,” he explained. “When I used the stuff I invented, I was telling a story, while I felt that the people who were imitating me were telling a joke. I felt other players tended to use tapping and false harmonics as a trick, instead of incorporating them into their vocabulary."

“Eruption” remains one of the most famous guitar solos in history, and has taken on a kind of mythological standing since Van Halen’s death in 2019. Yet for all of its glory, the guitar icon always believed it could have been more.

"To this day,” he said in ‘96, “whenever I hear it I always think, 'Man, I could've played it better.'"

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