In the 70's.

Their first American hit, Waterloo, was released in 1974. However, they formed a couple years earlier.

1971 in Stockholm Sweden

1970, when they were a cabaret act called Festfolket and Benny and Bjorn's "Hej, Gamle Man" song was famous. Most people think ABBA started in 1972 with "People Need Love". 1972 was their first year as a pop group under the long-winded name of Bjorn & Benny, Agnetha & Anni-Frid.

Between 1970and 1973. They had all already started a solo career. They came privately as two couples together and started progressively to work all together. In the beginning they just used their first names on the records. Later came the acronym ABBA. "- First live performance and the start of "Festfolk" An attempt at combining their talents occurred in April 1970 when the two couples went on holiday together to the island of Cyprus. What started as singing for fun on the beach ended up as an improvised live performance in front of the United Nations soldiers stationed on the island. Andersson and Ulvaeus were at this time recording their first album together, "Lycka", which was to be released in September 1970. Fältskog and Lyngstad added backing vocals on several tracks during June, and the idea of them all working together saw them launch a stage act, "Festfolk", which translates from Swedish to mean both "Party People" and "Engaged Couples", on 1 November 1970 in Gothenburg. The cabaret show attracted positive reviews. The foursome performed the Andersson and Ulvaeus hit "Hej, gamle man" ("Hi, Old Man"); the first recording credited to all four – and solo numbers from respective albums, but the foursome did not feel like working together, and soon concentrated on individual projects again.... - First record together "Hej, gamle man": "Hej, gamle man", a song about an old Salvation Army soldier, became the quartet's first hit. The record was credited to Björn & Benny and reached number 5 on the sales charts and number 1 on Svensktoppen, staying there for 15 weeks. In the first half of 1971, the four artists worked more together, adding vocals to the others' recordings. Fältskog, Andersson and Ulvaeus toured together in May, while Lyngstad toured on her own. Frequent recording sessions brought the foursome tighter together during the summer. - Forming the group (1970–1973): After the 1970 release of Andersson's and Ulvaeus' album "Lycka", two more singles credited to 'Björn & Benny' were released in Sweden, "Det kan ingen doktor hjälpa" ("No doctor can help with that") and "Tänk om jorden vore ung" ("Imagine if the Earth were young"), but clearly with more prominent vocals by Fältskog and Lyngstad - and with moderate chart success. Fältskog released her fourth album in 1971 and married Ulvaeus on 6 July 1971. Andersson, Ulvaeus, and Fältskog started performing together on a regular basis during the summer of 1971. Stig Anderson, founder and owner of Polar, was determined to break into the mainstream international market with music by Andersson and Ulvaeus. "One day the pair of you will write a song that becomes a worldwide hit", he predicted. Stig encouraged Ulvaeus and Andersson to write a song for Melodifestivalen, and after two rejected entries in 1971, Andersson and Ulvaeus submitted their new song "Säg det med en sång" ("Say It With A Song") for the 1972 contest, and they chose newcomer Lena Anderson to perform. The song won third place, encouraging Stig, and became a huge hit in Sweden. The first signs of foreign success came as a surprise, as the Andersson and Ulvaeus single "She's My Kind of Girl" was released by Epic in Japan in March 1972, giving the duo a Top 10 hit. Two more singles were released in Japan, "En Carousel" (earlier version of "Merry-Go-Round") and "Love Has Its Ways" (a song they wrote with Koichi Morita). - First hit as 'Björn, Benny, Agnetha & Anni-Frid' Ulvaeus and Andersson persevered with their songwriting and experimented with new sounds and vocal arrangements. "People Need Love" was released in June 1972, featuring guest vocals by the women, who were now given much greater prominence. Stig Anderson released it as a single, credited to Björn & Benny, Agnetha & Anni-Frid. The song reached #17 in the Swedish combined single and album charts, enough to convince them they were on to something. The single also became the first record to chart for the quartet in the United States, where it peaked at #114 on the Cashbox singles chart and #117 on Record World's singles chart. Billed as Björn & Benny (with Svenska Flicka), it was released there on Playboy Records. However, according to Stig Anderson, "People Need Love" could have been a much bigger American hit, but a small label like Playboy Records did not have the distribution resources to meet the demand for the single from retailers and radio programmers. The foursome decided to record their first album together in the autumn of 1972, and sessions began on 26 September 1972. The two women shared lead vocal on "Nina, Pretty Ballerina", on this day, and the two women's voices combined in harmonies for the first time gave the foursome an idea of the qualities of their combined talents. - "Ring Ring": For 1973, the band and their manager Stig Anderson decided to have another try at the Melodifestivalen, this time with the song "Ring Ring." The studio sessions were handled by Michael B. Tretow, who experimented with a "wall of sound" production technique that became the wholly new ABBA sound. Anderson arranged an English translation of the lyrics by Neil Sedaka and Phil Cody and they thought this would be a surefire winner, but in the Melodifestivalen, on 10 February 1973, it placed third, and thus never reached the international contest. Nevertheless the proto-group put out their first album, called Ring Ring. The album did well and the "Ring Ring" single was a hit in many parts of Europe and also in South Africa, but Stig Anderson felt the true breakthrough could only come with a UK or US hit. - Official naming: In early 1973, Stig Anderson, tired of unwieldy names, started to refer to the group privately and publicly as ABBA. At first, this was a play on words, as Abba is also the name of a well-known fish-canning company in Sweden (itself an acronym). However, since the fish canners were unknown outside Sweden, Anderson came to believe the name would work in international markets. As a coincidence, "abba" exists as a word in the Aramaic and Hebrew languages. It means "father", but in the more informal familiar sense that saying "dad" might connote. A competition to find a suitable name for the group was held in a Gothenburg newspaper. The group was impressed with the names "Alibaba," "FABB," and "Baba", but in the end all the entries were ignored and it was announced in the summer that the name "ABBA" was official. Later the group negotiated with the canners for the right to the name. "ABBA" is an acronym formed from the first letters of each group member's name: Agnetha, Björn, Benny and Anni-Frid (Frida). The first 'B' in the logo version of the name was "mirror-image" reversed on the band's promotional material from 1976 onwards and became the group's registered trademark. The first time the name is found written on paper is on a recording session sheet from the Metronome Studio in Stockholm, dated 16 October 1973. This was first written as "Björn, Benny, Agnetha & Frida", but was subsequently crossed out with "ABBA" written in large letters on top." Source and further information: http://en.wikipedia.org/wiki/ABBA