Exploring Social Network Service (SNS) communication as a global phenomenon, this book investigates how digital youth engage in computer-mediated communication (CMC) in the era of social media. Particularly focused on their uses of emoji, their motivations, attitudes and interpretations of emoji use across languages, Emoji Speak provides the first book-level discussion looking at youth-to-youth SNS communication and emoji use. Presenting the results of empirical investigation through large-scale surveys, SNS corpora, and interviews with a wide pool of international youth participants, it suggests that emoji use among young people is leading to the emergence of a new, 'social' grammar.