The concept of normalization revolves around narrowing down to a specific subject matter and then relating that subject matter to other related subject matters by primary and foreign key relationship. For example, If you have an entity called employee. If under employee you have say Last_name, Birth_date, Order_date, Order_quantity it will be better if we create another entity called Order and take out everything about order from the employee table to the order table. We can then create primary and foreign keys to link both table.. By this example, we have narrowed down the subject matter to employee and order respectively- this is normalization.