Marketers want to engage audiences. Yet most media spend still targets content, using this as a surrogate for the audiences that frequently consume this content. Until recently, it was technically and commercially unreasonable for both buyers and sellers to negotiate for subsets of broadcast media content (e.g., television, radio, newspapers, magazines, billboards, etc.) based on buyer-defined audience segments. With the advances in programmatic media planning and execution, we have seen these barriers erode amid the rise of audience-based tailored advertising.