Cost-per-engagement (CPE) bidding, also referred to as engagement-based pricing, is an internet advertising model where advertisers only pay when users actively engage with ads.
Video Cost-per-engagement
Examples
Advertisers can pay for lightbox ads (a type of expandable ad that can expand to a very large size) on a CPE basis, which means that publishers generate earnings from lightbox ads when users choose to engage with the ads, e.g., by hovering over them for two seconds to expand the ads.
Another example of engagement-based pricing allows advertisers to pay only when the user clicks on an ad and spends more than 15 seconds reading the landing page.
In terms of Influencer marketing, where brands pay individual content creators to produce and post sponsored content, Cost Per Engagement is calculated as the total cost of the content (a social post for example) divided by the total number of likes, comments, shares, etc.
Maps Cost-per-engagement
References
Source of the article : Wikipedia