An invoice is a financial transaction document that is given to a customer to show exactly how much is owed to the business for goods purchased on credit. In sequence, an invoice is normally given after the customer has sent a purchase order to the business, detailing what he/she would like to order. Prior to that, the business would have sent the customer a quotation to show how much the item/s cost.
An invoice is documents given from suppplier to customer as (demand ) for payment .it is usuallycomes where there is credit purchases it contains name and address of seller and purchaser , invoice number so that it can keep track of all it's invoice ,date of transaction , description of what being sold , quantity and unit price of what being sold , total amount of invoice including any details of sales tax. And remember that
Invoice received from suppplier will be used to update company's accounting record .