What is OLAP in Business Intelligence?

Online Analytical Processing, a category of software tools that provides analysis of data stored in a database. OLAP tools enable users to analyze different dimensions of multidimensional data. For example, it provides time series and trend analysis views. The chief component of OLAP is the OLAP server, which sits between a client and a database management systems (DBMS). The OLAP server understands how data is organized in the database and has special functions analyzing the data.

A good OLAP interface has writes an efficient sql and reads an accurate data from db. To design and architect having good knowledge on DB understanding the report requirements.