There's no shortage of books published in the past several years that have focused on the recent history of social media companies and the founders of the tech giants running them. In “Extremely Online: The Untold Story of Fame, Influence, and Power on the Internet,” Taylor Lorenz makes a valuable and entertaining contribution to that collection by telling the story through the prism of the users, creators and influencers who have shaped social media and its impact on our culture. Lorenz, techno