The Internet had been around for a while when on July 5, 1993, the New Yorker magazine featured a cartoon that, in the minds of some, marked its real arrival. “On the Internet,” says the dog at the computer screen to his canine friend, “nobody knows you’re a dog.” I knew it was time to write this book when I woke up one morning, downloaded my digital edition of the October 8, 2012, Ne…