M.A.K. Halliday (1925–2018) was the founder of Systemic Functional Linguistics (SFL) and, undoubtedly, one of the most influential linguists of his time, credited with changing the way that language and linguistics have been taught. SFL, as an appliable theory that approaches language as social semiotic, is the study of the relationship between language and its functions in social settings. Moreover, SFL conceives of language as a resource for making meaning and organizes language systemically as a huge network of interrelated choices of meaning. This book is an introduction to the life and seminal works of Halliday. Targeting both SFL and non-SFL scholars, this book introduces Halliday’s life and work in simple terms, expounds his theoretical conceptions, illustrates how his theories have been applied to various areas of linguistics and offers additional readings for researchers who want to explore this area further. Divided into six sections covering Hallidayan connections, theory and architecture of language, Hallidayan conceptions of language, systems and the modes of meaning, and applications of SFL, this accessible introduction is a key resource for researchers and students within the fields of linguistics and applied linguistics.