The need to repair habitat and restore forest structure and function is recognized throughout the temperate and boreal zones as a component of sustainable forest management (Dobson et al. 1997; Krishnaswamy and Hanson 1999; Minnemayer et al. 2011). Forest restoration is a complex task, complicated by diverse ecological and social conditions, which challenges our understanding of forest ecosystems. The term “restoration” is used indiscriminately and it is difcult to dene in such a way that encompasses all situations found in the literature and in practice (Lamb et al. 2012; Stanturf et al. 2014b). Generally, restoration is seen as symmetric with degradation (Putz and Redford 2010; Simula and Mansur 2011): An undisturbed forest in a natural or historical condition can be degraded, and a degraded forest can be restored to that natural or historical condition. As it will become apparent, reality is more complicated and the fully restored state is probably unattainable (Cairns 1986; Stanturf and Madsen 2002; Hobbs et al. 2011). Terminology, however, is not merely an academic issue; denitions related to forestry and restoration are used under several international conventions such as climate change and biodiversity where distinctions and nuance have important policy implications (FAO 2002). The objective of this chapter is to provide a conceptual framework for the terms used throughout this book, to facilitate understanding of the diverse cultural and ecological contexts for restoration ofCONTENTS1.1 Introduction 1 1.2 Historical Context 2 1.3 Degradation and Restoration Processes 4