Celebrities Evan Rachel Wood and Lady Gaga participated as well.
Soon, the campaign traveled from Twitter to other social platforms, including Facebook.
Many told stories of harassment during childhood, their teen years, adulthood and several more shared multiple accounts.
Perpetrators were often trusted clergy, family members, strangers, coworkers, authority figures or friends.
Some victims of sexual harassment said the social media campaign gave them the courage to speak up.
Others spoke up for those who chose not to publicly participate.
The magnitude of the campaign and its reach didn’t surprise everyone, but many people, including several men, wrote they had trouble reading all of the stories.
Still, others felt the campaign was flawed, that it triggered painful feelings for victims and put the pressure on them to “do the work.”
As the hashtag flooded social media, others wondered: “Now what?”
A resounding answer on Twitter: Start teaching consent, kindness and respect.
Follow the hashtag #MeToo on Twitter, on Facebook and on Instagram.
Milano's initial tweet followed the New York Times' Oct. 5 investigation into decades of sexual harassment allegations against Hollywood producer Harvey Weinstein.
In a statement last week, Twitter chief executive Jack Dorsey also tweeted about the company's efforts to tackle abuse after it faced criticism for suspending actress Rose McGowan's account.