They posted hate speech and Hitler emojis. They also organized a rally in Charlottesville, Va., connecting several major white supremacy groups for an intimidating display of force. How white supremacists and neo-Nazis used their favorite social networks to craft and propagate their messages — at least until they were barred from the platform. Guest: Kevin Roose, who writes about technology for The Times. For more information on today’s episode, visit nytimes.com/thedaily.