After the violent white supremacist rally in Charlottesville, condemnations of the marchers' cause came quickly — except from the White House. President Trump made references to "many sides" and violent responses from counter-protesters. Conservative critics were more explicit, pinning blame for some violence on antifa, short for antifascist. So what is antifa, and who participates? Guest host Stephen Henderson, Pulitzer Prize-winning columnist for the Detroit Free Press, is joined by Mark Bray, author of the new book "Antifa: The Anti-Fascist Handbook." It traces antifa's history and tactics, from its origins fighting the wave of European fascism in the early 20th century to protests in Berkeley, California, and Charlottesville today. You'll also hear from Maria Stephan, director of the program on nonviolent action at the U.S. Institute of Peace and co-author of "Why Civil Resistance Works: The Strategic Logic of Non-Violent Conflict."