star schema separates business process data into facts and dimension

facts, which hold the measureable, quantitative data about a business ( about business)

dimensions, which are descriptive attributes related to fact data(description of production)

dimension : description of object( 对某个事物的描述），describe the different characteristics, or dimensions, of a business.

fact : description of behavior(对某个行为的描述）

Facts change regularly, and dimensions do not change, or change very slowly.