An invoice is a statement of charges delivered to a customer by a product or service provider. There are two applications for an invoice title. The label you give to a particular invoice form is a file title. The actual statement has a title in the header section as well.
The invoice title or name you give to your file is important to internal organization. You want a simple but clear title that helps you separate one file from another. For example, labeling one file as "Product Renewal Invoice" and another as "New Client Invoice" provides a clear distinction. In some cases, companies create different invoices to convey specific or additional types of information with particular customers. Clear titles allow for efficient file searches.
The header section of a typical invoice includes your company logo and address as well as the customer's details. It also includes an invoice title. On the invoice, the title alerts the customer to the specific purpose of the charges. A title such as "New Widget Order" communicates to the customer that the invoice includes charges for a new product order rather than charges for a previous order.