This book was written with the purpose of making fire dynamics science accessible to Firefighters and practitioners at all levels. Although fire dynamics is a scientific discipline, we have kept jargon and mathematics to a minimum wherever possible, with the express intention of this being a very basic introduction to fire dynamics. This book has been cited in academic papers, used as mandatory reading by the Institution of Fire Engineers' and used by many fire departments, training providers and organisations throughout the world.As we approached the five year anniversary, having delivered training and assistance to Firefighters all over the world, with the assistance of our friends at IFRA and other charitable organisations, alongside our day jobs as professional Firefighting Instructors, we reflected and bought the books forward to become even more helpful. Shan developed the IFE's International Tactical Firefighting (Compartment Behaviour Instructors' Programme), of which some of this book addresses parts of the learning outcomes required for successful completion- so we have listed them at the end of each chapter. More are linked in the sequels to this book and of course during the course. We also realized that during our travels, some Firefighters only have access to a cell phone as a source of information, the developing world often can't afford books- so this edition will also have an "e-copy" or "kindle"- within this we've also added hyper-links to public domain videos, kindly provided often by our friends, which are available on our YouTube channel which is all free. A big thank you to our friends globally for their support with that and we feel it helps to embed the simple learning in this edition. Hopefully those introduced will want to learn more and progress onto the more technical and detailed publications on this subject. Think of this book as the first 'stepping stone' onto more detailed and academic publications on this subject. A sound understanding of the fundamentals of fire development forms the essential foundation of safe and efficient fire and rescue operations. This empowers us to protect our colleagues and the communities we serve.