Reports from Canada say the suspect in the Toronto van attack made a reference to "Incel Rebellion" on Facebook. But what exactly is an "incel"?
Alek Minassian, 25, appeared in court on Tuesday, a day after a rental van struck pedestrians in the city, killing 10 and injuring 15.
Facebook confirmed to the BBC that Minassian was the author of a post which read in part: "The Incel Rebellion has already begun! We will overthrow all the Chads and Stacys! All hail the Supreme Gentleman Elliot Rodger!" The post also contained a reference to the message board 4chan.
"Incel" is short for "involuntarily celibate" and in particular refers to online groups of men who feel that they can't enter into sexual relationships.
The attitudes of men who visit the boards vary widely, but online they frequently vent anger against sexually prolific men ("Chads") and women ("Stacys"). More generally, incel forums often include rants aimed at feminism and women.
On Tuesday, another subreddit dedicated to incels, r/Malecel, was banned.
However, other similar boards remain active on Reddit, and many other sites play host to incel discussions.
Incel forums also - albeit sometimes ironically - include praise for Elliot Rodger, who killed six people in the rampage through Isla Vista, California in 2014 before turning the gun on himself.
Rodger left a rambling manifesto detailing his sexual frustration and his hatred of women and minorities.
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