OLAP (OnLine Analytical Processing), a technology supporting analytical capabilities against one or more of data sources. OLAP systems usually involve analyzing data that originated in a traditional database, but was then transformed into a multi-dimensional structure for easier visualization. Relational and multi-dimensional database models usually serve very different purposes; while the former is intended for read/write, transactional, high-volume activities, the latter is suited for low-volume, complex queries that span large quantities of data at any time. Relational databases have SQL as their query language; in contrast, multi-dimensional OLAP environments have no commonly accepted language, although the proprietary MDX language created by Microsoft is gaining acceptance. Related categories include: - Data mining, which attempts to discover trends and patterns in the data; - Data warehousing, which attempts to reconcile some or all of a company's data sources into a single all-encompassing database; - Data transformation tools, which provide the means to cleanse and manipulate data while transferring it from one location to another.