An insertion order (IO) is a formal document, often resembling a contract, that provides a comprehensive campaign overview. It includes critical information like campaign start and end dates, ad placement, format, dimensions, and the chosen pricing model (e.g., CPM or CPC). Additionally, it covers essential details related to the target audience, traffic sources, branding requirements, and other campaign-specific parameters. The IO also outlines specifics about banner sizes, ad placements, the web pages where the ads will appear, and the agreed pricing model and payment terms.