Book excerpt: Until well into recent times, a high level of connectivity existed among ecosystems. Through the ever-increasing extent and intensity of human exploitation of natural resources, however, the pattern of human activities as islands in a sea of nature has become reversed in most of the world's regions. Habitat fragmentation is now one of the most important causes of the decline in biodiversity. The main purpose of this review is to assist the understanding of the practical value of maintaining, enhancing, creating or restoring linkages.