Billie Eilish made approximately 111 million of her fans' day when she added them to her Close Friends group on Instagram on Thursday.

Users of the social media platform can share content to their Instagram Stories and share it with everyone or a selected group of chosen people on their Close Friends list. 

Millions of fans were elated when Billie – who slammed artists for 'wasteful releases' – shared a Story and they found out they were on her Close Friends list.

The What Was I Made For singer shared a low resolution photo of a hand in front of the night sky. 

Billie soon started trending on Twitter where fans shared their elation at being one of the Ocean Eyes singer's besties – on Instagram, at least. 

One fan shared a screenshot of Billie's IG Story and wrote: 'mom: why is billie eilish at your wedding??' me: that's my bestie.'

Another fan wrote: 'How I feel after seeing myself in Billie Eilish’s instagram close friends,' and shared a photo of Cillian Murphy holding his Oscar.

Yet another close friend of Billie's shared a photo of a woman dining with a cardboard cutout of a person and wrote: 'Me and Billie Eilish after she added me to her close friends.'

On Wednesday, the Bad Guy singer was one of more than 200 artists calling for the 'predatory' use of AI in the music industry to be stopped.

In an open letter, several of the world's biggest stars have warned the tech 'will set in motion a race to the bottom' if left unchecked.

The use of AI to steal artists' voices, likeness, and sound is an 'assault on human creativity', they said, and would 'destroy the music ecosystem.'

Issued by the Artists Rights Alliance (ARA), the letter calls for a ban on AI tools that undermine or replace human songwriters or their work.

The move is part of an industry-wide push for better regulation of generative AI, the technology behind chatbots like ChatGPT and image generators like Midjourney.

Katy Perry, Jon Batiste, Jon Bon Jovi, Nicki Minaj, Stevie Wonder, REM, Zayn Malik and Miranda Lambert are all among the artists who signed the letter.

Fears over the use of AI have mounted over recent months after a song using AI to mimic the voices of Drake and The Weeknd went viral online.

The letter warns that AI will 'infringe upon our rights and devalue the rights of human artists' if it is used irresponsibly.

'This assault on human creativity must be stopped. We must protect against the predatory use of AI to steal professional artists' voices and likenesses, violate creators' rights, and destroy the music ecosystem,' the letter says.