Ad Agencies
Ad agencies represent advertisers, giving them advice on where to run, designing the ad, and getting the ad in the newspaper, or "placing" the ad. When an agency places an ad in your newspaper, the assumption is that the agency helped sell their client into your newspaper and almost always provides a camera-ready, finished ad. Especially because the ad is camera-ready and therefore the newspaper's production department has one less ad to make, most newspapers give agencies a discount, usually 15% off the total cost of the ad.

In fact, this is how most ad agencies make money. The newspaper bills the ad agency for the full amount of the ad, the agency passes passes the bill along to their client, the client pays the agency and the agency pays the bill, less the 15% discount or as they call it, the commission. But at one point, retailers were claiming they were an ad agency as well and tried to take their volume or frequency discounts and then an additional 15% agency commission discount as well. This "double dipping" wasn't very fair and newspapers have done a couple of things to ensure the newspaper's kindness isn't abused.

First, many newspapers have strict guidelines on who is an agency and who isn't. For example, the so called agency must provide camera ready copy. It must have more than one client. And it must choose one discount or the other. Either the newspaper will bill the account at the non-discount or "open" or "commissionable" rate as it's also called (usually the most expensive rate) and the agency takes 15% off that, or they take frequency or volume discounts like everyone else, and make arrangements with their clients for alternative methods of payments for their assignments.