pernick and wilder say that, in the 1970s, clean technology was considered “alternative”. even at the start of the 21st century, the term "clean tech" was not yet widely used. but now, throughout much of the world, in trends large and small, there is "the beginning of a revolution that is changing the places where we live and work, the products we manufacture and purchase, and the development plans of cities, regional governments, and nations around the globe."