The science of prognosis: To forecast based on current trends.
The field of study are large scale, long term analyses of the social and economical development of society. It is to be stressed that such an analysis is a scientific prediction and not just a simple and vulgar (unscientific) prophecy. In plain English: Marxism and its claims of an inevitable revolution and the birth of a communist utopia are not concidered ‘good science’. A scientific prediction is a matter of universal conditional statements and an ‘if then’ logic. At least according to the futurologists.
In practice, however, it is hard to predict anything besides death and taxes—especially the future—and thus the attempts of charting future possibilities should never be taken at face value. Nonetheless, if you heed the limitations of this science the analyses it provides can broaden your perspective in a chronological way.
Oh, and for a cheap laugh read the past predictions of how the present would turn out …it's rather spooky when they got it right, though.