In the field of computer science, a reduced binary decision diagram (BDD) is a data structure that represents a Boolean function. It is a compressed representation of sets or relations. Unlike other compressed representations, operations are performed directly on the compressed representation, i.e. without decompression.

In popular usage, the term reduced ordered binary decision diagram (ROBDD) is used synonymously as ordered binary decision diagram (ROBDD), but with emphasised ordering and reduction aspects.