A variety of multidimensional data models have recently been proposed by both academic and industry communities. but consensus on formalism or even a common terminology has not yet emerged. In this chapter, we first discuss the requirements that an ideal conceptual multidimensional model should fulfill. These requirements are suggested by general information system modeling principles and the specific characteristics of OLAP applications. Building on these requirements, we then present a general conceptual multidimensional data model and show how it can be used to describe the basic aspects of a business application in a way that is easy to understand and independent of the criteria for actual data organization in the various systems. Starting from the characteristics of the model proposed, we summarize the general features that a multidimensional conceptual model should support. We then survey various multidimensional models proposed and relate their characteristics to these general features. Finally, we discuss the main points raised in the chapter and some problems that remain to be solved in this context.