What is the ice bucket challenge that popular personalities are taking?

The internet has gone viral with videos of celebrities and other popular personalities taking the " Ice Bucket challenge" and daring three others to do the same. Here is what you need to know about it:

What is the ice bucket challenge?

It's an effort to raise awareness of ALS where participants must dump a bucket of ice cold water and then dare someone to do the same. If they can't, the alternative is to donate $100 to the ALS association

How did it start?

The ice bucket challenge went viral on social media after a US baseball player and ALS patient, Pete Frates, floated the idea of the challenge in a video on a social networking site. He got the idea from a friend

The impact

More than 1.2 million videos were shared on Facebook between June 1 and August 13. The challenge was mentioned more than 2.2 million times on Twitter since July 29, after Frates' appeal

The funds

According to the ALS website, it has so far received nearly $23 million

What is ALS

Amyotrophic lateral sclerosis is also referred to as Lou Gehrig's Disease. It is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord

Incidence

ALS is thought to be affect 2 people every 1 lakh of the global population

Life expectancy

About 20% people with ALS live 5 years or more, up to 10% live more than 10 years and about 5% live up to 20 years after diagnosis

They took the challenge

Cristiano Ronaldo

Lady Gaga

Mark Zuckerberg

Brian Vickers

Satya Nadella

Bill Gates

Oprah Winfrey

Britney Spears