What are Dimensional Tables..?

Dimension Tables are also tables and contains descriptive information used to describe the rows in the fact table. look at the following fact table row....

There is no product Name, no staff name, no Customer name. With out  having these names, how do you describe the qty_sold as 1 and unit_sales_price as 200..?  We can't..!

By  looking prod_id (3), customer_id (5) in the product dimension and Customer dimension, we will get product name as "Santoor" and customer name  as "Jhon". So, by using dimensional tables we can describe fact rows with information such as product name, customer name etc..