(CNN)Age ain't nothing but a number. In Billie Eilish's case though, it's a big deal.
The pop singer-songwriter is 17 years old and the first artist born in the 2000s to hit No. 1, thanks to her debut album "When We All Fall Asleep, Where Do We Go?"
She's also the youngest woman to hit No. 1 since 2009 when Demi Lovato debuted with "Here We Go Again" at 16.
Here's four other things you should know about Billie Eilish.
She's the daughter of two actors
Billie Eilish Pirate Baird O'Connell was born to Maggie Baird and Patrick O'Connell on December 18, 2001 in Los Angeles.
Her mother, Baird, is known for her work on the film "Life Inside Out" and video game "Mass Effect 2," while O'Connell, her father, appeared in the movie "Iron Man"and TV show "The West Wing."
In 2018, she revealed she had Tourette's syndrome
Eilish opened up to fans on Instagram about living with Tourette's.
"i would love to get this straight so everyone can stop acting goofy..," she wrote on her story. "i have diagnosed tourettes. I've never mentioned it on the internet because nobody thinks I'm deadass..as well as...the fact that I've just never wanted people to think of tourettes every time they think of me."
Her Instagram handle is @wherearetheavocados
Eilish told the story behind the name of her Instagram handle in an interview with iHeartRadio.
About seven years ago, she was in her kitchen making a grilled cheese sandwich and wanted some avocados to go with it.
There were none to be found.
"I screamed at the top of my lungs, 'Where are the avocados?!' No one answered, no one helped me, I ended up not eating avocados with that grilled cheese," she said. "So I made up my username as a f***ing joke. Because I was like, this sh*t would be fire as my username."
She started as a dancer but stopped after she was injured
Her first hit, "ocean eyes," written by her brother Finneas O'Connell, was for a dance class.
She told the BBC she strained her growth plate, and her bone separated from her hip muscle. She hopes to slowly get back to dancing.
