Who's the most popular music act in the world right now?
While most would assume it's Taylor Swift, by at least one metric it's actually a confusingly named Korean pop band you might never even have heard of.
Seventeen — the 13-member group who are the biggest thing in the K-pop genre right now — had the biggest-selling album in the world last year, FML, according to data from the International Federation of the Phonographic Industry.
Demonstrating K-pop's ever-broadening appeal, this week they have become the first Korean act to play at the iconic Glastonbury Festival in the UK.
So who are Seventeen, how did they get so popular and why do they have so many members?
What is K-pop?
K-pop draws on a range of popular music styles and genres and is characterised by highly trained and polished artists and their immaculate synchronised dance routines.
It first became popular in Korea in the 1990s with US-influenced acts like Seo Taiji and Boys.
In the 2000s, artists like PSY, whose hit Gangnam Style was the first to get a billion views on YouTube, and BTS introduced the genre to new audiences worldwide.
According to Sarah Keith, a senior lecturer in media and music at Macquarie University, K-pop is much more than just a style of colourful and upbeat music.
"K-pop describes this way of creating music and artists [being identified] with talent spotting, then training and the packaging of the group, and the marketing," Dr Keith said.
Who is Seventeen?
Seventeen were first brought together in 2012 by Korean talent agency and record label Pledis Entertainment for a live-streaming show, Seventeen TV.
The show's two-hour episodes, which primarily featured the members practising their singing and dancing in their studio, were a big hit and went on for five seasons.
Audiences were able to catch a glimpse into the member's lives and work, creating a sense of closeness and giving them time to develop favourites, or "biases".
Financial difficulties at Pledis delayed the group's launch by two years, but in 2015 they finally made their formal debut in a showcase on one of Korea's biggest TV stations.
While the group initially had 17 members, in line with the name, over the course of the television show, members came and went and by the time they launched they only had 13.
The group is divided into three "sub-units": Hip-Hop (rappers), Vocal (singers), and Performance (dancers).
So with their name already being cemented with the fanbase, they developed a new rationale — with 13 members, and three sub-units coming together as one, they made Seventeen.
All the members have different roles, even if in some they might only sing for a few seconds.
Unlike most manufactured K-pop outfits, the members of Seventeen write and produce much of their own music.
Their first five-track EP, 17 Carat, peaked at number 13 on the Billboard US World Chart.
Their biggest hits, like Super, have racked up 212 million views on YouTube and they have multiple songs in their discography with more than 100 million views.
In 2022, they went on their third world tour, which was made possible through their efforts to promote themselves aggressively abroad, especially in places like Japan, where they cemented a loyal fan base.
By releasing at least 10 songs every year since 2015, in Korean, English and Japanese, they have relentlessly marketed themselves to appeal to more people, while consistently putting out new content for their older fans.
Why do they have so many members?
Even 13 people in a band might seem like a lot but that's not unusual in the K-pop genre.
Other big K-pop groups like Stray Kids have eight, and NCT has even more, with 26 members.
Many of these groups, like Seventeen, have sub-units that allow the members to have their turn in the spotlight, and give the management company the opportunity to play with group dynamics.
"Ultimately, there's not much difference in launching a four-member group to an eight-member group in terms of investment and work, but the eight-member group will give you more value because there are more members for people to enjoy and form connections with," Dr Keith said.
"It also gives the audience more hooks to get into the group."
Why are Seventeen so popular?
Jen, who runs a local Seventeen fan community in Melbourne, told the ABC that she only got into K-pop recently.
"I grew up listening to Fall Out Boy, and then things like EDM [electronic dance music] and didn't think that I liked K-pop," she said.
"During COVID, I was searching through Spotify and getting ads with sounds that I liked and I would shazam it — and it was K-pop."
For many people, K-pop is synonymous with catchy songs with colourful music videos like Gangnam Style and BTS's Butter, but Jen said that it was much more diverse than that.
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"I was always into EDM sounds and I listened to [Seventeen's] song Don't Wanna Cry, which has EDM elements, and I was like, 'Where has this been all my life?'" Jen said.
Jen said Seventeen often interacted with their fans directly and were extremely responsive to what their audience wanted, as well as popular music trends, and produced songs accordingly.
"They'll tap into actual music trends as well like, dance music, or they listen to Blink-182 or now Charlie XCX and are aware of what's trending," she said.
Because Seventeen wrote their own music, fans felt a greater connection to the lyrics, she said.
Why do K-pop bands do so well in album sales?
Seventeen's FML sold 6.4 million units worldwide in 2023, more than double Taylor Swift's 1989 (Taylor's version), which sold 2.8 million units, according to the International Federation of the Phonographic Industry (IFPI) Global Album Sales Chart.
But Seventeen are far from the only K-pop act doing well on the albums charts.
Nineteen out of the 20 highest-selling albums globally last year were K-pop groups.
"Some fandoms and fans collectively organise to purchase K-pop albums so that their artist performs well in the charts," Dr Keith said.
Companies also release "lucky draw" albums which each include a random photocard out of a set so fans have to purchase multiple copies to either get the photocard they want, or even the full series.
Fans also trade photocards of their favourite group members, or "biases".
Some of these cards go for up to $3,000 on the secondary market, with fans creating communities to buy and sell cards alongside other merchandise around the world.
While artists like Taylor Swift are now being talked about for actively engaging with her fans through the release of multiple versions of her albums, Dr Keith said she was adopting strategies used in the K-pop industry for years.
