From emails to social media, from instant messaging to political memes, the way we produce and transmit culture is radically changing. This book uses, for the first time, cultural evolution theory to analyze how information spreads, and how it affects our behavior in the digital age. Online connectedness and digital media allows access to networks where cultural transmission is possible, increasing both the availability of cultural models (from whom we can copy) and our reach (the number of individuals who can copy from us). This poses new problems, and new opportunities (Chapter 1). A cognitive and evolutionary approach suggests that we are wary learners, and the power of social influence, either online or offline, is often overestimated (Chapter 2). The background developed in the initial chapters into the details of different online phenomena is used: the tendency to copy popular individuals (Chapter 3), popular opinions (Chapter 4), or exchange information only with same-minded individuals (Chapter 5). The spread of online misinformation is then scrutinized at length (Chapter 6), proposing that to understand the phenomenon we need to understand why, generally, some information is more successful in spreading than other. The last two chapters examine how online, digital, transmission is different from other forms of cultural transmission, providing more "fidelity amplifiers" (Chapter 7), and how this could affect future cultural cumulation (Chapter 8). Overall, it is proposed that a "long view" to the current situation, based on a personal perspective of cognitive and evolutionary approaches to culture, suggests that some of the dangers of digital, online, interactions may have been overestimated, and the opportunities still ahead of us are discussed.