With one tweet, Alyssa Milano has sparked an important dialogue about sexual assault and harassment, and tens of thousands of Twitter users — celebrities like Lady Gaga and Sarah Hyland among them — have come forward with stories.

After having a conversation a friend, the former Charmed star used Twitter Sunday (Oct. 15) to encourage women to write "me too" if they had ever been sexually assaulted or harassed.

Milano's request came at an important moment, considering the fallout from the allegations of sexual impropriety that have been — and continue to be — leveled at Harvey Weinstein.

What followed is a movement that has swept up the Internet. The hashtag #metoo began trending, and was tweeted nearly half a million times in 24 hours. Musicians, actors and celebrities like Hilarie Burton (who recently detailed a 14-year-old encounter with Ben Affleck), Debra Messing and Milano's Charmed co-star Rose McGowan, who has tried to speak up about being raped by Weinstein (and whose Twitter account was suspended for her comments), joined the masses to stand in solidarity with fellow women.

"My hope is people will get the idea of the magnitude, of just how many people have been affected by this in the world, in our lifetimes, in this country," Milano told the Associated Press. "The most important thing that it did was to shift the conversation away from the predator and to the victim."

Take a look below at the celebrities who've joined the #MeToo chorus by sharing on social media.

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