The vast majority of all email sent every day is spam, a variety of idiosyncratically spelled requests to provide account information, invitations to spend money on dubious products, and pleas to send cash overseas. Most of it is caught by filters before ever reaching an in-box. Where does it come from? As Finn Brunton explains in Spam, it is produced and shaped by many different populations around the world: programmers, con artists, bots and their botmasters, pharmaceutical merchants, marketers, identity thieves, crooked bankers and their victims, cops, lawyers, network security...