The internet can feel like a cause-a-minute factory. Every day there's a new way to color your profile photo to show support, a deserving Kickstarter to fund, or an online petition to sign. Save the whales, close the jails, open your wallets. Click like to share and then go watch a YouTube about adorable meerkats. Then there's #MeToo.

Social media feeds have been filling this week with the #MeToo hashtag, sharing raw, personal stories or simply raising their hand. In a way not usually seen with online movements, people are seeing everyone join in, from celebrities like Reese Witherspoon and Jennifer Lawrence, to political figures like Senator Elizabeth Warren, to close family members, old hometown acquaintances, and work colleagues.

"It is a watershed moment for survivors and allies," Lisa Huebner, an associate professor of women's and gender studies at West Chester University of Pennsylvania, told NBC News.

Over 825,000 tweets have been posted using the hashtag #MeToo since Sunday. Within 24 hours, 4.7 million people globally had engaged in the "Me Too" conversation on Facebook, generating over 12 million posts, comments and reactions, a spokesperson for the social media giant told NBC News. More than 45 percent of people in the U.S. are Facebook friends with a person who has posted a "Me Too" status update.

#MeToo , I was 14, he was a stranger , I was babysitting,I didn't lock the door..he walked in..I was overpowered..

I am not ashamed — drixy (@drix78) October 17, 2017

While the movement adopts some of the forms of previous online activist movements, it seems to have surpassed them in terms of scope and depth. It cuts across all categories.

"#MeToo...creates connection through an authentic display of vulnerability and intimacy, which is rare to see on such a mass scale," Mary Joyce, Impact Design Director at Harmony Labs, a New York-based media impact accelerator, told NBC News.

A revolution of survivors

The "Ice Bucket Challenge" raised over $115 million in 2014, the ALS foundation reported, with some of it going to fund the discovery of a new potential treatment. After Senator Elizabeth Warren was silenced on the Senate floor for continuing to read a letter against Attorney General nominee Senator Jeff Sessions, "She Persisted" trended on social media and appeared on protest signs, t-shirts, hoodies, and mugs.

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During the "Arab Spring," the number of tweets about political change in Egypt swelled from 2,300 a day to 230,000 a day in the week running up to former Egyptian president Hosni Mubarak's resignation, and the top 23 protest videos received 5.5 million views, according to a University of Washington study.

"This is a much more powerful way to show support. You're actually saying 'this includes me.'"

But activists and experts say #MeToo feels different.

"On one side, it's a bold declarative statement that 'I'm not ashamed' and 'I'm not alone.' On the other side, it's a statement from survivor to survivor that says 'I see you, I hear you, I understand you and I'm here for you or I get it,'" women's activist Tarana Burke, who started the "Me Too" campaign 10 years ago, told CNN.

Related: Weinstein Accusations Prove Women's Courage Is Contagious

#MeToo isn't jumping on a trendy, partisan bandwagon. It's not as emotionally easy as adding an emoji to your username. And it's not even about politics, it's about changing an entire cultural system around one specific set of oppressive behaviors.

"When there's a big tragedy and you have an overlay on your profile photo, that's not necessarily saying 'I'm a part of it.' This is a much more powerful way to show support. You're actually saying 'this includes me,'" said Julie Wiest, an assistant professor of sociology at West Chester University of Pennsylvania.

"It represents a new kind of meme, one in which the personal content of each iteration far outweighs the formal structure," said digital strategist Joyce. "For instance, a photo overlay of a flag or banner is highly impersonal, highly formal. The Ice Bucket Challenge fell somewhere in the middle. It was personalized, but most who participated did not themselves have ALS."

The rallying cry's volume has reached new decibel levels because it comes at a key moment. Actress Alyssa Milano brought the "me too" phrase to a new, wider audience when over the weekend she encouraged all victims to post "MeToo" to demonstrate the cultural "scope and magnitude" of sexual assault and harassment. The post came in the wake of graphic accounts by scores of women who accused now-fired Hollywood producer Harvey Weinstein of serial and systematic abuse.

If you’ve been sexually harassed or assaulted write ‘me too’ as a reply to this tweet. pic.twitter.com/k2oeCiUf9n — Alyssa Milano (@Alyssa_Milano) October 15, 2017

Not just Hollywood

One in five women report being the victim of sexual assault, according to surveys, but it's estimated that the true numbers are even higher. For every person who is brave enough to make a #metoo post, statistically speaking, there are many more who could but are choosing not to.

In June, comedian Bill Cosby went to trial for sexual assault charges — just one of the 50 allegations of sexual assault publicly made against him.

Earlier this year, it was that former Fox News anchor Bill O'Reilly paid millions of dollars over the years to quietly settle sexual assault and harassment lawsuits at the network. His former boss, Roger Ailes, the founding CEO of Fox News, resigned after he was accused by female Fox anchors of sexual harassment, and one sued him for not renewing her contract after she refused his alleged advances.

And in late 2016, a tape surfaced of then-candidate Donald Trump saying that he grabs women "by the pussy." Later when asked by a reporter what he would do if his daughter, Ivanka, faced the behavior that Ailes was accused of, he said he hoped she would leave the company or change careers.

When sexual assault is perpetuated and protected within a culture of shame and silence, speaking up is an act of revolution.

"They're breaking the silence," said Huebner.