"Planning as a subject for study is one of the most multidisciplinary: practice and theory cut across and draw on a breadth of social sciences and other influences. It is an integrative concern, an endlessly dynamic and interesting field for study and reflection, Moreover the aims, activities and implications of planning affect us all. The concepts included here and the way that they are applied have been shaped and reshaped by policy makers and practitioners, by commentators and academics within planning and across the contributory disciplines. These ideas and labels are actively shaping practice and are shaped by practice \2013 they are fluid and open to appropriation. All of these concepts therefore reflect and can be used to understand planning activity in different ways. In selecting these key concepts we have included ideas that provide a basis for understanding planning and the factors that shape the relationship between society and environment. Planning policies tend to reflect social choices about resource use and the organisation of the built and natural environment."--Page [1].