Book excerpt: Fully updated and revised, this fourth edition of Halliday's Introduction to Functional Grammar explains the principles of systemic functional grammar, enabling the reader to understand and apply them in any context. Halliday's innovative approach of engaging with grammar through discourse has become a worldwide phenomenon in linguistics. Updates to the new edition include: Recent uses of systemic functional linguistics to provide further guidance for students, scholars and researchers More on the ecology of grammar, illustrating how each major system serves to realise a semantic system A systematic indexing and classification of examples More from corpora, thus allowing for easy access to data Halliday's Introduction to Functional Grammar, Fourth Edition, is the standard reference text for systemic functional linguistics and an ideal introduction for students and scholars interested in the relation between grammar, meaning and discourse.