Invoices are an IOU from the customer. When selling a product or service to a customer, businesses typically provide an invoice stating what products or services were sold and the amount the customer has agreed to pay. Sometimes they are paid immediately, others are paid over 15-90 days or longer.
Unpaid receivables or invoices have value. A typical business that extends credit will have ten to twenty percent of its annual sales tied up in accounts receivable at any given moment. AmeriStrength pays you cash now for your accounts receivable and collects the future payments on the purchased invoices.