What does bid pacing control in an ad auction?

Bid pacing is an essential mechanism in programmatic advertising that helps manage how and when bids are placed in ad auctions. The primary function of bid pacing is to regulate the timing of bids throughout the duration of the campaign. It determines which auctions to enter or skip based on factors such as the remaining budget, performance, and the overall strategy of the advertising campaign.

When bid pacing is set effectively, it ensures that the ads remain competitive without exhausting the budget too quickly or failing to spend adequately over the campaign's intended timeline. In essence, it allows advertisers to optimize their participation in auctions, ensuring that their ads appear at the right moments when they are most likely to yield favorable outcomes.

In contrast, the other options do not accurately capture the role of bid pacing. While the number of bids submitted, the duration of the ad campaign, and the cost per click are all important aspects of media buying and ad auctions, they are not directly controlled by bid pacing itself. Instead, these factors are often influenced by the overall strategy and settings of the ad campaign.