An invoice or bill is a document issued by a seller to the buyer, indicating the products, quantities, and agreed prices for products or services the seller has provided the buyer. An invoice indicates the buyer must pay the seller, according to the payment terms. The buyer has a maximum amount of days to pay these goods and are sometimes offered a discount if paid before.
In the rental industry, an invoice must include a specific reference to the duration of the time being billed, so rather than quantity, price and discount the invoicing amount is based on quantity, price, discount and duration. Generally speaking each line of a rental invoice will refer to the actual hours, days, weeks, months etc being billed.
It is up to the merchant whether value added tax is included in the price of its products and services. Documents that include value added tax are referred to as "invoices" while documents that do not include value added tax are referred to as "payment records".
It is important in a business because it keeps records in the transaction easier rather than having it manual.
