Online analytical processing (OLAP) is a core component of a complex business intelligence (BI) architectural stack. Even as vendors begin to explore alternative technologies for "slicing" and "dicing" large data sets, OLAP engines, servers, and models still play a key role in most BI solutions for small, midsize, and especially large enterprises. While information and knowledge management (I&KM) professionals need to familiarize themselves with emerging post-OLAP solutions, traditional OLAP approaches will remain an essential component in most BI installations for at least the next five years.