Casey and Mark recall how they met and the online communities they have been a part of. Mark shares some of his earliest online community experiences and thinks about the nature of community tools. How do tools influence their community? What can we learn from the Teen Wolf fandom? Casey teaches Mark about Dark Social. Casey and Mark discuss the communities that are being built around Twitch.tv and how communities form around broadcasters and broadcasting tools. Casey talks about "effortlessly positive communities". Casey and Mark discuss the Twitch Plays Pokémon experiment.