The term Decision Support (DS) is used often and in a variety of contexts related to decision making. Recently, for example, it is often mentioned in connection with Data Warehouses and On-Line Analytical Processing (OLAP). Another recent trend is to associate DS with Data Mining. This is the case in the project SolEuNet , which attempts to exploit these two approaches in a complementary way in order to support difficult real-life problem solving. Unfortunately, although the term ‘Decision Support’ seems rather intuitive and simple, it is in fact very loosely defined. It means different things to different people and in different contexts. Also, its meaning has shifted during the recent history. Nowadays, DS is probably most often associated with Data Warehouses and OLAP. A decade ago, it was coupled with Decision Support Systems (DSS). Still before that, there was a close link with Operations Research (OR) and Decision Analysis (DA). This causes a lot of confusion and misunderstanding, and provokes requests for clarification. The confusion is further exemplified by the multitude of related terms and acronyms that are either equal to, or start with ‘DS’: Decision Support, Decision Sciences, Decision Systems, Decision Support Systems, etc. This paper attempts to clarify these issues. We take the viewpoint that Decision Support is a broad, generic term that encompasses all aspects related to supporting people in making decisions. First, we present the results of a survey of WWW documents related to DS. On this basis, and on the basis of relevant literature and our previous experience in the field of DS, we provide a classification of DS and related disciplines. DS itself is given a role within Decision Making and Decision Sciences. Some most prominent DS disciplines are briefly overviewed: Operations Research, Decision Analysis, Decision Support Systems, Data Warehousing and OLAP, and Group Decision Support. … Decision Support (DS)