THE Swedish pop-hit machine that sold tens of millions of records, ABBA return on Friday with their first album after a nearly 40-year break.


Here are five things to know about the band.


- One name, four first names, and herring -

Formed in stages in the early 70s, the group had its first successes in Sweden, but struggled to find an identity. After ditching the name "Festfolket" and an unsuccessful naming contest launched in a newspaper, Agnetha Faltskog, Bjorn Ulvaeus, Benny Andersson and Anni-Frid Lyngstad finally settled on "ABBA" an acronym of their first names.


The only problem was that the name was already used by a fish cannery. After a phone call to the director of the company, Agnetha got permission to use the name in exchange for an easy promise never to go into the fish business or embarrass the company. Abba's pickled herring is still sold in most supermarkets in Sweden, and a staple on Swedish dinner tables at holidays such as Midsummer and Christmas.


- The triumph of 'Waterloo' -

After losing out in 1973 with the single "Ring Ring", the quartet managed to win Sweden's Melodifestivalen, thereby getting to represent their country at Eurovision 1974, held in Brighton in the south of England.


With their star-shaped guitars and tight satin costumes, ABBA triumphed with "Waterloo", relegating Grease diva Olivia Newton-John to sixth place.


In front of millions of viewers, a phenomenon was born. The song, referencing Napoleon's famous defeat, topped charts across Europe.


It was just the first of a string of hits, including Mamma Mia (1975) and Dancing Queen (1976) first performed at the wedding of Sweden's King Carl XVI with Queen Silvia in June 1976.


- Crazy costumes -

Initially intended to stand out from the crowd of Eurovision contestants, the sparkling costumes became an ABBA trademark.


"I asked Bjorn: 'What would you like, what can I produce for you?' And he answered: 'Nothing is too crazy'," Owe Sandstrom, the designer of the group's famous outfits, told AFP.


It was a call to extravagance that the costume designer eagerly embraced, blending influences from cabarets, the circus and the animal kingdom.


Sequins, pearls, crystals and all that glitters were liberally draped over the ABBA stars. One of Sandstrom's favourites was inspired by flamenco and worn by Bjorn during a performance of hit "Chiquitita" (1979) at a UNICEF charity concert.


- Sweden, a champion of musical exports -

Even today, only three countries in the world export more music than they import: the US, the UK and Sweden, according to a recent independent study commissioned by industry group Export Music Sweden.


With hundreds of millions of albums sold, ABBA helped the Nordic country of 10 million people punch above its weight.


Bands like Roxette, Ace of Base, The Cardigans, or more recently Swedish House Mafia, Lykke Li and the late Avicii, have taken up the torch.


Unofficial figures say ABBA has sold as many as 400 million albums, but according to Carl Magnus Palm, author of several books on the group, 150 to 200 million is closer to reality. In any case, the band is one of the best-selling bands in the world.


- Two marriages and two divorces -

While ABBA is a quartet, it also formed two couples.


Agnetha and Bjorn were married in 1971. Then in 1978, Frida and Benny, who had been together for several years, also got hitched.


But the trials of managing relationships as superstars became too much to bear and in 1979, Agnetha and Bjorn divorced, followed by Frida and Benny in 1981.


Not letting a good heartbreak go to waste, Agnetha and Bjorn's break-up is believed to have inspired one of the groups most iconic songs, "The Winner Takes It All" (1980).


In 1981, ABBA released a final album and the following year the band split up. But their success continued, notably with the compilation "ABBA Gold" released in 1992.