The untitled fourth studio album by the English rock band Led Zeppelin, commonly known as Led Zeppelin IV, was released on 8 November 1971 by Atlantic Records. Produced by the band's guitarist, Jimmy Page, it was recorded between December 1970 and February 1971, mostly in the country house Headley Grange. The album contains the band's most well-known recording, the eight-minute-long "Stairway to Heaven".

The informal recording environment inspired the band, allowing them to try different arrangements of material and create songs in various styles. After the band's previous album Led Zeppelin III (1970) received lukewarm reviews from critics, they decided their fourth album would officially be untitled and represented instead by four symbols – one chosen by each band member – without featuring the name or any other details on the cover. Unlike the prior two albums, the band was joined by guest musicians: the singer Sandy Denny on "The Battle of Evermore", and the pianist Ian Stewart on "Rock and Roll". As with prior albums, most of the material was written by the band, though there was one cover song, a hard rock re-interpretation of the Memphis Minnie blues song "When the Levee Breaks".

The album was a critical and commercial success and is Led Zeppelin's best-selling album, having shipped over 37 million copies worldwide. It is one of the best-selling albums in the United States and of all time, while critics have regularly placed it high on lists of the greatest albums of all time.

Following the release of Led Zeppelin III in October 1970, the group took a break from live performances to concentrate on recording a follow-up. They turned down all touring offers, including a proposed New Year's Eve gig that would have been broadcast on television. They returned to Bron-Yr-Aur, a country house in Snowdonia, Wales, to write new material.

Recording sessions for the album began at Island Records' new studios on Basing Street in London on 5 December 1970, with the recording of "Black Dog". The group had considered Mick Jagger's home, Stargroves as a recording location, but decided it was too expensive. They subsequently moved the following month to Headley Grange, a country house in Hampshire, England, using the Rolling Stones Mobile Studio and the engineer Andy Johns, with the Stones' Ian Stewart assisting. Johns had just worked on engineering Sticky Fingers and recommended the mobile studio. The guitarist and producer Jimmy Page later recalled: "We needed the sort of facilities where we could have a cup of tea and wander around the garden and go in and do what we had to do." This relaxed, atmospheric environment at Headley Grange also provided other advantages for the band, as they were able to capture spontaneous performances immediately, with some tracks arising from the communal jamming. The bassist and keyboardist John Paul Jones remembered there was no bar or leisure facilities, but this helped focus the group on the music without being distracted.

Once the basic tracks had been recorded, the band added overdubs at Island Studios in February. The band spent five days at Island, before Page then took the multitrack tapes to Sunset Sound in Los Angeles for mixing on 9 February, on Johns' recommendation, with a plan for an April 1971 release. Mixing would take ten days, before Page travelled back to London with the newly mixed material. The band had a playback at Olympic Studios. The band disliked the results, and so after touring through the spring and early summer, Page remixed the whole album in July. The album was delayed again over the choice of cover and whether it should be a double album, with a possible suggestion it could be issued as a set of EPs.

"Black Dog" was named after a dog that hung around Headley Grange during recording. The riff was written by Page and Jones, while the a cappella section was influenced by Fleetwood Mac's "Oh Well". The singer Robert Plant wrote the lyrics, and later sang portions of the song during solo concerts. The guitar solos on the outro were recorded directly into the desk, without using an amplifier.

"Rock and Roll" was a collaboration with Stewart that came out of a jam early in the recording sessions at Headley Grange. The drummer John Bonham wrote the introduction, which came from jamming around the intro to Little Richard's "Keep A-Knockin'". The track became a live favourite in concert, being performed as the opening number or an encore. It was released as a promotional single in the US, with stereo and mono mixes on either side of the disc.

"The Battle of Evermore" was written by Page on the mandolin, borrowed from Jones. Plant added lyrics inspired by a book he was reading about the Scottish Independence Wars. The track features a duet between Plant and Fairport Convention's Sandy Denny, who provides the only female voice to be heard on a Led Zeppelin recording. Plant played the role of narrator in the song, describing events, while Denny sang the part of the town crier representing the people.

"Stairway to Heaven" was mostly written by Page, and the bulk of the chord sequence was already worked out when recording started at Basing Street Studios. The lyrics were written by Plant at Headley Grange, about a woman who "took everything without giving anything back". The final take of the song was recorded at Island Studios after the Headley Grange session. The basic backing track featured Bonham on drums, Jones on electric piano and Page on acoustic guitar. The whole group contributed to the arrangement, such as Jones playing recorders on the introduction and Bonham's distinctive drum entry halfway through the piece. Page played the guitar solo using a Fender Telecaster he had received from Jeff Beck and had been his main guitar on the group's first album and early live shows. He put down three different takes of the solo and picked the best to put on the album.

The song was considered the standout track on the album and was played on FM radio stations frequently, but the group resisted all suggestions to release it as a single. It became the centrepiece of the group's live set from 1971 onwards; in order to replicate the changes between acoustic, electric and twelve-string guitar on the studio recording, Page played a Gibson EDS-1275 double-neck guitar during the song.

"Misty Mountain Hop" was written at Headley Grange and featured Jones playing electric piano. Plant wrote the lyrics about dealing with the clash between students and police over drug possession. The title comes from J. R. R. Tolkien's The Hobbit. Plant later performed the track on solo tours.

"Four Sticks" took its title from Bonham playing the drum pattern that runs throughout the song with four drum sticks, and Jones played analog synth. The track was more difficult to record than the other material on the album, requiring numerous takes. It was played live occasionally in early 1971. The song was also re-recorded with the Bombay Symphony Orchestra in 1972. This version appears on the deluxe edition reissue of the group's 1982 album Coda. The song was also reworked for Page and Plant's 1994 album No Quarter: Jimmy Page and Robert Plant Unledded.

"Going to California" is a quiet acoustic number. It was written by Page and Plant about Californian earthquakes, and trying to find the perfect woman. The music was inspired by Joni Mitchell, of whom both Plant and Page were fans. The track was originally titled "Guide To California"; the final title comes from the trip to Los Angeles to mix the album.

"When the Levee Breaks" comes from a blues song recorded by Memphis Minnie and Kansas Joe McCoy in 1929. The track opens with Bonham's heavy unaccompanied drumming, which was recorded in the lobby of Headley Grange using two Beyerdynamic M 160 microphones which were hung up a flight of stairs; output from these were passed to a limiter. A Binson Echorec, a delay effects unit, was also used. Page recalled he had tried to record the track at early sessions, but it had sounded flat. The unusual locations around the lobby gave the ideal ambience for the drum sound. This introduction was later extensively sampled for hip hop music in the 1980s. Page and Plant played the song on their 1995 tour promoting No Quarter: Jimmy Page and Robert Plant Unledded.

Three other songs from the sessions, "Down by the Seaside", "Night Flight" and "Boogie with Stu" (featuring Stewart on piano), were included four years later on the double album Physical Graffiti. An early version of "No Quarter" was also recorded at the sessions.

After the lukewarm, if not confused and sometimes dismissive, critical reaction Led Zeppelin III had received in late 1970, Page decided that the next Led Zeppelin album would not have a title, but would instead feature four hand-drawn symbols on the inner sleeve and record label, each one chosen by the band member it represents. The record company were strongly against the idea, but the group stood their ground and refused to hand over the master tapes until their decision had been agreed to.

Page has also stated that the decision to release the album without any written information on the album sleeve was contrary to strong advice given to him by a press agent, who said that after a year's absence from both records and touring, the move would be akin to "professional suicide". Page thought, "We just happened to have a lot of faith in what we were doing." He recalled the record company were insisting that a title had to be on the album, but held his ground, as he felt it would be an answer to critics who could not review one Led Zeppelin album without a point of reference to earlier ones.

Releasing the album without an official title has made it difficult to consistently identify. While most commonly called Led Zeppelin IV, Atlantic Records catalogues have used the names Four Symbols and The Fourth Album. It has also been referred to as ZoSo (which Page's symbol appears to spell), Untitled and Runes. Page frequently refers to the album in interviews as "the fourth album" and "Led Zeppelin IV", and Plant thinks of it as "the fourth album, that's it". The original LP also has no text on the front or back cover, and lacks a catalogue number on the spine.