Why do we add a laughing emoji when nothing's funny? Why does texting 'k' feel colder than texting 'ok'? And what does all the jargon mean in social gaming? Jenny Lederer explores how our everyday digital conversations -texts, tweets, emojis, vlogs, and dating apps-are reshaping language and social life. Far from being trivial, online talk offers a living laboratory for understanding how humans create meaning, negotiate identity, and build relationships in a connected world. Blending traditional, cognitive, and digital linguistic theory with real-world examples, App Chat invites readers to see their own digital communication in a new light. Every LOL, emoji, and ghosted text reveals something deeper about how communication works, both online and off. Playful yet rigorous, this book is perfect for students curious about language, linguistic theory, culture, and technology, as well as anyone who's ever wondered: how does the medium of communication shape the message communicated?