System-wide blacklists are created based on which of the following?

System-wide blacklists are primarily created based on known bot traffic. This approach helps advertising platforms and marketers safeguard their inventory and ensure that ad impressions are delivered to real users rather than automated bots that generate fake traffic. By identifying and categorizing sources of bot traffic, these blacklists prevent advertisers from spending their budgets on non-human interactions, therefore optimizing the effectiveness of their campaigns.

The focus on known bot traffic is crucial because it directly impacts the quality of impressions and the overall integrity of the advertising ecosystem. Maintaining high standards through blacklisting questionable traffic sources helps advertisers achieve their performance goals and improves trust in programmatic advertising. In contrast, high-quality impressions, user engagement rates, and brand collaboration efforts, while important to overall campaign strategies and performance metrics, do not serve the same purpose in the context of creating system-wide blacklists focused on preventing fraud.