Michele Zappavigna is a Senior Lecturer in the School of Arts and Media at the University of New South Wales, Australia. Her major research interest is the discourse of social media, and she has published widely on this topic in a range of books and journals. J.R. Martin is Professor of Linguistics at the University of Sydney, Australia. His research interests include systemic theory, functional grammar, discourse semantics, register, genre, multimodality and critical discourse analysis, focusing on English and Tagalog. He was elected a Fellow of the Australian Academy of the Humanities in 1998, and awarded a Centenary Medal for his services to Linguistics and Philology in 2003.