We need buildings for housing and for the other services they provide for us and our activities. Our demands stimulate supply, creating a market. As the market supplies and services these buildings it makes demands on national resources, changes regional economies and populations, affects the quality of life and creates costs and benefits. Planning professionals set out to regulate the market, sometimes removing imperfections, sometimes creating them. Their policy decisions need to take account of the likely changes in industry, technology, life styles and expectations and the demands they will generate. Because there are never sufficient resources to meet these demands, hard decisions have to be taken. It is essential that the decision makers are as well-informed as possible. This text describes how the market operates, giving a picture of the economics of development, use and management of the built environment. The author pays particular attention to the issues and options for the future, with a view to improving decision-taking in planning.