This chapter introduces the study of emoji as a form of social media paralanguage. It delves into the semiotic versatility of emoji as ‘picture characters’ enabling users to express a wide range of meanings through their use with language in social media communication. The book approaches emoji as a form of paralanguage due to their close dependency on the meanings conveyed in their written co-text and their social context. The chapter highlights the significance of the social semiotic perspective to emoji-text relationships adopted in the book with its focus on understanding how they converge with the meanings made in other semiotic modes. It concludes by introducing the structure of the book and the focus of the upcoming chapters on both emoji-text relations and social affiliation.