Working with Odoo 11 - Third Edition

Customer

This field is automatically populated if you create an opportunity from the customer form. You can, however, assign a different customer if you like. This is not a required field, so if you have an opportunity that you do not wish to associate with a customer, that is perfectly fine. For example, you may leave this field blank if you are attending a trade show and expect to have revenue, but do not yet have any specific customers to attribute to the opportunity.