DCO is an advertising technique that integrates different elements of an ad unit in real-time, as the ad is being served, based on information about the user. This is done by using Data Feeds and Sets of Rules for the automatic customization of an ad based on criteria like device, location, time, placement, etc. https://medium.com/@jamesparl352/understanding-the-significance-of-dynamic-creative-optimization-in-programmatic-advertising-89ee6e4112c9