On-Line Analytical Processing, or OLAP, refers to a class of applications that allows a user to interactively perform multi-dimensional analysis against a set of data. With an OLAP tool, the user can interactively explore the data, summarizing the data across different dimensions and drilling down to see a greater level of detail. OLAP tools are designed around a data architecture that can respond to the user’s queries quickly, without making the user wait, as opposed to running a complex query against a relational database where it might take minutes or even hours to deliver the results.