invoice

This term functions as both a formal record of a transaction and the action of requesting payment. In a business context, it carries a professional, contractual tone, distinguishing it from a simple bill, which can be more casual or consumer-oriented. It implies a structured document that serves as a legal or accounting trail for auditing purposes. As a noun, it is a standard countable entity. When used as a verb, it describes the administrative process of billing, often occurring at specific intervals like monthly or quarterly cycles.