In 1966, London-based session guitarist Jimmy Page joined the blues-influenced rock band the Yardbirds to replace bassist Paul Samwell-Smith. Page soon switched from bass to lead guitar, creating a dual lead guitar line-up with Jeff Beck. Following Beck's departure in October 1966, the Yardbirds, tired from constant touring and recording, began to wind down. Page wanted to form a supergroup with him and Beck on guitars, and the Who's Keith Moon and John Entwistle on drums and bass, respectively. The group never formed, although Page, Beck, and Moon did record a song together in 1966, "Beck's Bolero", in a session that also included bassist-keyboardist John Paul Jones.
The Yardbirds played their final gig in July 1968 but they were still committed to several concerts in Scandinavia, so drummer Jim McCarty and vocalist Keith Relf authorized Page and bassist Chris Dreja to use the Yardbirds' name to fulfill the band's obligations. Page and Dreja began putting a new line-up together. Page wanted the Jaywalker’s Terry Reid to fill the vocalist spot for his proposed new group, the New Yardbirds. Reid had already committed to go on the road for two tours with The Rolling Stones and another with Cream (as an opening act on the 1968 US Tour). Reid suggested to Page that if he were compensated for the gig fees he would miss out on and Page would call Keith Richards to explain why Reid had to pull out of the US tours, Reid would try some things out with Page.
It never happened and Reid told Page to consider a young Birmingham-based singer, Robert Plant, instead, having previously seen Plant's Band of Joy as a support act at one of his concerts. Reid also suggested Page check out their drummer John Bonham. Meanwhile, Dreja left to take up photography. John Paul Jones, at the suggestion of his wife, asked Page about the vacant position, and the guitarist eagerly invited Jones to collaborate. Page later explained:
“I was working at the sessions for Donovan's Hurdy Gurdy Man, and John Paul Jones was looking after the musical arrangements. During a break, he asked me if I could use a bass player in the new group I was forming. He had a proper music training, and he had quite brilliant ideas. I jumped at the chance of getting him.”
The four played together for the first time in a room below a record store on Gerrard Street in London. Page suggested that they attempt "Train Kept A-Rollin’”. "As soon as I heard John Bonham play", Jones recalled, "I knew this was going to be great ... We locked together as a team immediately".
The band completed the Scandinavian tour as the New Yardbirds, playing together for the first time in front of a live audience at Gladsaxe Teen Clubs in Denmark, on September 7, 1968. Later that month, they began recording their first album, which was based on their live set. The album was recorded and mixed in nine days, and Page covered the costs. After the album's completion, the band were forced to change their name after Dreja issued a cease and desist letter, stating that Page was allowed to use the New Yardbirds moniker for the Scandinavian dates only. One account of how the new band's name was chosen held that Moon and Entwistle had suggested that a supergroup with Page and Beck would go down like a "lead balloon", an idiom for disastrous results. The group dropped the 'a' in lead at the suggestion of their manager, Peter Grant, so that those unfamiliar with the term would not pronounce it "leed". The word "balloon" was replaced by "zeppelin", a word which, according to music journalist Keith Shadwick, brought "the perfect combination of heavy and light, combustibility and grace" to Page's mind.
Grant secured a $143,000 advance contract ($1 million today) from Atlantic Records in November 1968—at the time, the biggest deal of its kind for a new band. Atlantic was a label with a catalogue of mainly blues, soul, and jazz artists, but in the late 1960s it began to take an interest in British progressive rock acts. Record executives signed Led Zeppelin without having ever seen them. Under the terms of their contract, the band had autonomy in deciding when they would release albums and tour, and had the final say over the contents and design of each album. They would also decide how to promote each release and which tracks to release as singles.
The band began their first tour of the UK on October 4 1968, still billed as the New Yardbirds; they played their first show as Led Zeppelin at the University of Surrey in Battersea on 25 October. Tour manager Richard Cole, who would become a major figure in the touring life of the group, organized their first North American tour at the end of the year. Their debut album, Led Zeppelin, was released in the US during the tour (during dates at the Fillmore West, actually) on January 12 1969, and peaked at number 10 on the Billboard chart. According to Steve Erlewine, the album's memorable guitar riffs, lumbering rhythms, psychedelic blues, groovy, bluesy shuffles and hints of English folk music made it "a significant turning point in the evolution of hard rock and heavy metal".
In their first year Led Zeppelin completed four US and four UK concert tours, and also released their second album, Led Zeppelin II. Recorded mostly on the road at various North American studios, it was an even greater commercial success than their first album, and reached the number one chart position in the US and the UK. The album further developed the mostly blues-rock musical style established on their debut release, creating a sound that was "heavy and hard, brutal and direct", and which would be highly influential and frequently imitated. Steve Waksman has suggested that Led Zeppelin II was "the musical starting point for heavy metal".
The band saw their albums as indivisible, complete listening experiences, disliking the re-editing of existing tracks for release as singles. Grant maintained an aggressive pro-album stance, particularly in the UK, where there were few radio and TV outlets for rock music. Without the band's consent, however, some songs were released as singles, particularly in the US. In 1969 an edited version of "Whole Lotta Love", a track from their second album, was released as a single in the US. It reached number four in the Billboard chart in January 1970, selling over one million copies and helping to cement the band's popularity. The group also increasingly shunned television appearances, citing their preference that their fans hear and see them in live concerts.
Following the release of their second album, Led Zeppelin completed several more US tours. They played initially in clubs and ballrooms, and then in larger auditoriums as their popularity grew. Some early Led Zeppelin concerts lasted more than four hours, with expanded and improvised live versions of their repertoire. Many of these shows have been preserved as bootleg recordings. It was during this period of intensive concert touring that the band developed a reputation for off-stage excess.
John Paul Jones, quoted in the New Musical Express, February 1973, said, “As far as I’m concerned, the key Zeppelin gig, the one that put everything into focus, was one that we played on our first American tour at the Boston Tea Party (January 26, 1969). We’d played our usual one hour set, using all the material for the first album and Page’s White Summer guitar piece and by the end, the audience just wouldn’t let us offstage. It was in such a state that we had to start throwing ideas around, just thinking of songs that we might all know or that some of us knew a part of and work it out from there.
So we’d go back on and play things like “I Saw Her Standing There” and “Please Please Me”, old Beatles favorites. I mean, just anything that would come into our head and the response was quite amazing. There were kids actually bashing their heads against the stage – I’ve never seen that happen at a gig before or since, and when we finally left the stage, we’d played for four plus hours.
Peter (Grant) was absolutely ecstatic. He was crying, if you can imagine that, and hugging us all. You know with this grizzly bear hug. I suppose it was then that we realized just what Led Zeppelin was going to become.”