Social media platforms face a reckoning over hate speech

In this June 4 file photo, a woman looks at the plywood covering the windows of a Starbucks store in downtown Naperville, Ill., as Naperville residents used hearts to post messages in support of the Black Lives Matter movement. Starbucks is the latest company to say it will pause social-media ads after a campaign led by civil-rights organizations called for an ad boycott of Facebook, saying it doesn't do enough to stop racist and violent content. (AP Photo/Nam Y. Huh, File)

For years, social media platforms have fueled political polarization and hosted an explosion of hate speech. Now, with four months until the U.S. presidential election and the country’s divisions reaching a boiling point, these companies are upping their game against bigotry and threats of violence.