Korean pop boy band BTS will be one of the presenters at the 2019 Grammy Awards on Sunday night, according to Billboard. It will be the first time the group presents an award in the United States.

K-pop has become increasingly popular outside of Korea, but no group has quite achieved the international success of BTS. The seven-member group was the most tweeted about music artist in 2017 and most tweeted about celebrity overall in 2018, beating LeBron James. The group has been nominated for a Grammy for best recording package. They were the first K-pop group to top the Billboard Hot 100 Artist chart, and last year they became the first K-pop group to speak at the United Nations.

Just who are these Korean heartthrobs that the world has fallen for? Here's everything you need to know about the group:

Who are they? 

BTS is a seven member Korean pop music group, consisting of RM, Jin, Suga, J-Hope, V, Jimin and Jungkook. The group made their musical debut in 2013 with their album "2 Cool 4 Skool." 

What does BTS stand for? 

In Korea, BTS stands for Bangtan Sonyeondan, which means Bulletproof Boy Scouts. Internationally they are also known as the Bangtan Boys. As of 2017, the members announced that they would also be known as Beyond the Scenes, as a part of a brand change.

What is the "BTS Army"

Fans of the K-pop group call themselves ARMY, an acronym for "Adorable Representative M.C for Youth." The fans are known for their passionate support of the group, as seen by the band's popularity on Twitter.  When it was announced they would present at the Grammys, the hashtag "BTSxGRAMMYS" quickly started trending.  

What records have they broken?

To understand the scope of how popular the group has become, you only have to look at the records they've achieved. Their album "Love Yourself: Tear" was the first Korean album to reach No. 1 on the Billboard top 200. They're also the first Korean group to have a platinum single and a gold album recognized by the Recording Industry Association of America (RIAA). Their music video for "Idol" is the fastest music video ever to hit 100 million views. 

Their influence reaches outside the world of music as well. They were the first Korean group to speak at a United Nations conference, and won the reader's poll for TIME Magazine's Person of the Year in 2018.

The 61st Grammys will be hosted by Alicia Keys and be broadcast live from the Staples Center in Los Angeles online and on CBS at 8:00 P.M ET. The show is set to feature multiple performances, including appearances by Camila Cabello, Cardi B, Janelle MonĂ¡e, Miley Cyrus, H.E.R., Brandi Carlile, Shawn Mendes, Kacey Musgraves, Dan + Shay and Post Malone with the Red Hot Chili Peppers.