In order to be able to handle fires in buildings safely and effectively, and to avoid being caught by surprise and ending up in situations we shouldn't be in, we must have knowledge of all the factors that affect the development of the fire. This includes basic knowledge and a good understanding of, among other things, how different types of materials react when exposed to heat in different ways, how such materials contribute to the spread and development of a fire, and how the environment, such as a room or a surrounding wind, can affect the development and spread of the fire. This book is primarily written for basic training courses in the fire service, but this does not, of course, exclude its usefulness in other contexts or for other target groups.