An invoice is a commercial document that specifies the details of goods or services sold by a supplier to a customer. The major feature of an invoice is that it specifies the particulars of goods bought, such as the quantity, price, and description of the goods, as well as any applicable taxes or discounts. This information helps the buyer verify the accuracy of the purchase and serves as a record for future reference. In summary, the major feature of an invoice is that it specifies the details of goods or services sold.