Celebrities such as Justin Bieber, Taylor Swift and Selena Gomez are pouring buckets of ice water on themselves but it's not to stay cool for the summer - they're doing it for the sake of raising awareness about ALS (Amyotrophic lateral sclerosis), or better known as Lou Gehrig's disease.

According to TIME, it is believed that the ice bucket challenge originated in Boston, where former Boston College baseball player Pete Frates, diagnosed with ALS in 2012, started the ALS awareness campaign on social media. The challenge? Post and nominate three people on your social media feed to either pour a bucket of ice water on themselves, or donate $100 towards ALS research.

TIME reports that 1.2 million unique videos have been posted on Facebook to date, and celebrities have begun challenging each other in order to grow the campaign.

This week, Justin Timberlake accepted the challenge by Boston Marathon bombing survivors, and videotaped himself and a group of friends being soaked by a bucket of ice water.

In recent days, the challenge spread to prominent figures of all kinds, including Bill Gates, Jimmy Fallon and Ellen DeGeneres.

Some notable pop stars who recently took to Instagram to accept the challenge include Justin Bieber (who accepted the challenge from manager Scooter Braun), Taylor Swift (who accepted the challenge from Ingrid Michaelson) and Selena Gomez (who accepted the challenge from Taylor Swift).

Taylor even took it one step further and for her giant group of friends who are seen in the video participating, she also reveals that a $100 donation on behalf of each person there will be going towards the ALS Foundation.

The movement is showing no signs of slowing down so expect to continue seeing celebrities participating in the challenge in the next several days. In the meantime, check out the videos below of Bieber, Swift and Gomez bravely pouring ice water on themselves.

If you would like to contribute to the cause, visit the ALS Association for more information.

Justin Bieber accepts the challenge from Scooter Braun

Taylor Swift and Jaime King pour buckets of ice water on one another

Selena Gomez accepts the challenge from Ryan Seacrest & Taylor Swift