The terms section of an invoice can be as simple or complex as you would like, dependent on your billing standards. At the very least, this should include when the invoice is due for instance, if you expect payment within thirty days (fairly standard), simply put “30 Days.” (You could also put “15 Days” or even “Immediate” if you don’t particularly like the client.) On the bottom, labeled explicitly, bolded if needed. Next to each item, list the hourly rate, hours worked and subtotal amount. Descriptions should be short and to the point, and all delivery dates indicated.
If you have been given one, be sure it appears conspicuously. This practice is usually found in larger companies.