 We will begin with a few brief historical remarks  (Section 2),  and then turn to some general questions about supervenience, such as whether it is explanatory and whether it is guarantees entailment  (Section 3).  We will then explore the various versions of supervenience in some detail  (Section 4).  The technical work is interesting in its own right, but it is obviously made more interesting by the fact that the different varieties of supervenience may be useful for different philosophical purposes. Thus, although most of this entry will be concerned with supervenience itself rather than its applications, we will end with a discussion of some of the substantive philosophical issues to which supervenience is relevant  (Section 5).