DENVER, CO - NOVEMBER 9: Halsey performs at the Gothic Theater in Denver, Colorado on November 9, 2015. (Photo by Seth McConn
Seth McConnell/The Denver Post via Getty Images

Last year, Halsey lived in Internet obscurity (save for her thousands upon thousands of diehard followers on Twitter and Tumblr). For the rest of the world, she was simply the voice behind that "Ghost" song, if they were lucky enough to hear it. 

Today, it was announced that the 21-year-old singer has officially sold out Madison Square Garden, less than a month after the Aug. 13, 2016 show was announced. To put it in perspective: Just a few months ago she was playing less-than 1,000 capacity rooms. This is huge, people!

The news arrived via Billboard. Halsey told the publication:

"The fact that my fans made this happen is groundbreaking. This is seriously unbelievable. Like literally unbelievable. I don't believe it -- someone show me the proof."

So sweet! Make sure to read all about Halsey's mental health discussion, why the world needs the lady and click through 10 ways to be a badass: a guide to her style.