sentences:  Practitioners of the discipline previously concentrated on extrapolating present technological, economic or social trends, or on attempting to predict future trends, but more recently they have started to examine social systems and uncertainties and to build scenarios, question the worldviews behind such scenarios via the causal layered analysis method (and others) create preferred visions of the future, and use backcasting to derive alternative implementation strategies.Apart from extrapolation and scenarios, many dozens of methods and techniques are used in futures research.At the end of the 20th century, the world was at a major crossroads.