You can create ad-hoc invoices as and when you want, or set up an order record to define when invoices should be generated automatically (eg. each month, quarter, or year). Invoices that are generated automatically can optionally be e-mailed to the client automatically, or you can send individual invoices to clients yourself.
Invoices can contain an unlimited number of itemised entries including HTML descriptions, with a summary of net, tax, gross, and shipping fees shown at the end. Invoices can also show a summary of payments received for the invoice and the total left outstanding.
It is easy to incorporate your own logo and colour scheme on an invoice, and if you have access to PHP coding skills, you can even create your own invoice template to give your invoices a unique look.