There's a reason hit songs offer such guilty pleasure--they're designed that way. Over the last two decades a new type of hit song has emerged, one that is almost inescapably catchy. Pop songs have always had a "hook," but today's songs bristle with them: a hook every seven seconds is the rule. The song machine explores what the new hits may be doing to our brains and listening habits, especially as music services use streaming data to gather music into new genres invented by algorithms based on listener behavior. Revelatory and original, this book will change the way you listen to music.