A video, a post, a photo, a meme, a phrase or a song can suddenly turn into a craze, spread out into the world and quickly colonise computers, smartphones, television, newspapers, our attention and even our minds. Why do certain ideas circulate more widely than others? What makes an image or a cultural product more or less viral? The book helps to understand the mechanisms that govern there production and the transmission of ideas, ensuring their propagation and success or, alternatively, sanctioning their failure.