Electronic invoicing is a form of electronic billing. E-invoicing methods are used by trading partners, such as customers and their suppliers, to present and monitor transactional documents between one another and ensure the terms of their trading agreements are being met. These documents include invoices, purchase orders, debit notes, credit notes, payment terms and instructions and remittance slips. These documents can be exchanged in a number of ways including EDI, XML, or CSV files. They can be uploaded using emails, virtual printers, web applications or FTP sites. The company may use imaging software to capture data from PDF or paper invoices and input it into their invoicing system. This streamlines the filing process while positively impacting sustainability efforts. Some companies have their own in house e-invoicing process. However many companies will hire a third party company to implement and support these e-invoicing processes and to archive the data that passes through them on their own servers. E-invoicing includes so many different technologies and entry options, it is used as an umbrella term to describe any method by which an invoice is electronically presented to a customer for payment.