Data Dimension

A Data Dimension is a set of data attributes pertaining to something of interest to a business.  Examples of dimensions are things like "customers", "products", "stores" and "time".

For users of Data Warehouses, data dimensions are entry points to numeric facts (e.g. sale, profit, revenue) that a business wishes to monitor.

For example, a business might want to know how may blue widgets were sold at a specific store in Los Angeles last month.

Dimensional Model

A data dimension can be hierarchical.  For example, "days" can be grouped into "months", "months" into "quarters" and quarters into "fiscal years" or "calendar years".  This allows fact data to be easily aggregated,  summarized and presented.