Underdelivery refers to a situation in which an advertising campaign does not deliver the number of impressions, clicks, or conversions that were promised or expected. Underdelivery can occur for a variety of reasons, such as changes in market conditions, changes in consumer behavior, technical problems, or errors in campaign setup or targeting. Underdelivery can be a problem for advertisers, because it can result in lower-than-expected performance, and can lead to missed opportunities or lost revenue. Advertisers can take steps to prevent underdelivery, such as setting realistic performance goals, monitoring campaigns closely, and making adjustments as needed. In some cases, advertisers may be able to negotiate make-goods or credits with the publisher or platform if underdelivery occurs.