A commercial discount is a discount applied individually to each item or service invoiced in a document.
This directly affects the price of each product in a document, and is calculated from an entered percentage value.
This amount will be subtracted from the gross amount to which taxes or withholdings may later apply.
This type of discount may also be offset by the global discount, which has a cumulative role in relation to the commercial discount.
To find out what a global discount is, see this FAQ.