Social media has been flooded with videos of people pouring buckets of ice water on their heads. It is not just another silly trend, but a movement to raise awareness and funds for amyotrophic lateral sclerosis (ALS), better known as Lou Gehrig’s disease. CNN reports that the trend has swept up a variety of people, including politicians such as Senator Cory Booker from New Jersey, Governor Chris Christie, Governor Bobby Jindal, and Senator Kelly Ayotte. Instead of pouring ice water on his head, President Obama has opted to contribute funds to the ALS Association.

The premise of the challenge is simple. After receiving a challenge, a person can either: 1) pour a bucket of ice water on his or her own head and invite others to the challenge, or 2) donate $100 to the ALS Association. The videos gather attention, challenging others brings them in, and those who prefer to stay warm and dry can still show their support by giving money to fight ALS and find a cure.

According to the ALS Association, ALS is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. The progressive degeneration of the motor neurons in ALS eventually leads to their death. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed.

Huffington Post shares a story of an ALS patient that wanted to join in on the challenge as well. Kreg Palko and his daughter joined in on the challenge, nominating others, and thanking everyone who had participated for raising awareness and money to fight ALS.