What document serves as a purchase order between a seller of advertising and a buyer?

The correct document that serves as a purchase order between a seller of advertising and a buyer is the Insertion Order. This document outlines the specifics of the advertising campaign, including details such as the ad formats, placement, pricing, duration, and other contractual obligations agreed upon by both the buyer and seller.

An Insertion Order acts as a formal agreement that confirms the transaction and sets the terms for the advertising placement, making it essential for both parties to understand their responsibilities. By specifying all necessary details, it ensures clarity and helps prevent any misunderstandings during the advertising execution.

The other options do not perform the same function. For instance, an Ad Agreement typically encompasses broader terms and conditions of the advertising relationship but may not be as detailed regarding individual campaign specifics as the Insertion Order. A Billing Statement is primarily focused on financial transactions rather than the specifics of the ad buy itself, and a Campaign Overview generally provides a summary of the advertising strategy and goals, rather than acting as a formal purchase order.