It began in the aftermath of allegations against Harvey Weinstein.
Many Twitter users responded, including celebrities.
Several men in Hollywood and in the media lost jobs over sexual harassment and assault allegations, including Kevin Spacey, Matt Lauer and Charlie Rose.
The women who came forward to tell their stories of harassment were named Time's People of the Year.
Meanwhile, the commander-in-chief was also the tweeter-in-chief. Donald Trump did not stop tweeting once he became president.
He frequently used the platform to attack opponents. But one particular tweet, with a typo that complained about "constant negative press covfefe," triggered a Twitter frenzy.
The most-liked tweet of the year came from former President Barack Obama, who tweeted an image and Nelson Mandela quote after the violence in Charlottesville, Virginia. It was also the second-most retweeted tweet.
On Instagram, the most-liked photo of the year was a Beyonce post from February announcing she was pregnant with twins. It was liked more than 11 million times. Beyonce gave birth to the twins in June.
The most viewed YouTube post of the year was the music video for "Despacito," with more than 4.5 billion views. It was also the most shared piece of content on Facebook for the year, according to the content tracking website Buzzsumo.
For NY1, our post of a man stealing a fire truck in Manhattan got a greater response on Facebook than any other. It generated more than 8,300 reactions and was viewed more than 1.2 million times.
Our tweet that generated the biggest response of the year was a video of city law enforcement members and City Councilman Jumaane Williams supporting free agent NFL quarterback Colin Kaepernick. It was retweeted more than 5,500 times, including by Kaepernick himself.