Children spend a significant amount of time interacting online rather than face-to-face. Yet we know very little about the language they use during interaction, whether they are gaming or texting. Drawing on cutting-edge research, this timely book applies Conversation Analysis (CA) techniques to investigate children's online language and interaction. Tudini provides a step-by-step analysis of authentic posts made by children on social media, messaging apps and gaming platforms, highlighting linguistic and interactional features. The book addresses the risks inherent in children's online interaction and the role of protective adults, yet also celebrates children's linguistic creativity and ability to adapt to new forms of communication. It also provides principled advice on how to support children in integrating online interaction into their lives productively and safely, to assist parents and teachers. Addressing a highly topical area, it is essential reading for students and researchers of applied linguistics, communication, education and sociology.