Coasts are particularly dynamic and the morphology of the coast is continually changing in response to various processes operating at different rates. Coastal landforms are extremely changeable and coastal habitats change over a range of spatial and temporal scales; recognition of these variations is necessary in order that planning and management can be effective. The increasing realisation that human impacts are affecting our coastlines has promoted the concept of vulnerability. Successful management of coastlines, including mitigation of adverse impacts, must be based on an understanding of natural patterns of change. When a trajectory of change is detected, it is often difficult to determine the extent to which it is the outcome of human impact or whether it is part of the natural pattern of change that might have occurred anyway. The complexity and intricacy of the feedbacks surrounding human use of the coast and coastal resources mean that there is rarely consensus on the degree to which human actions have modified natural processes. This chapter examines the patterns, directions and rates of change that coasts undergo. It provides a conceptual basis that underpins any consideration of the extent of human impact. The conceptual framework is illustrated with examples drawn from tropical and subtropical coasts.