Return on Investment (ROI) or Return on Ad Spend (ROAS) are often used interchangeably in the media and paid marketing world to represent the value generated by specific marketing initiatives. It can be analyzed at a channel or campaign perspective, although channel managers who are managing a specific channel can use ROI/ROAS to optimize at a more granular level for their channel, such as ad groups and keywords for Paid Search managers, or placements and ads for Display and Video managers.