input: Placement Similar to content categories, in DoubleClick for Publishers you can create placements to group a collection of inventory (ad slots) that an advertiser might want to target. Unlike content categories, you can report on placements. Say, for example, you operate a news site. You might create one placement that includes ad slots for all skyscraper ads on your site. You might create another placement that includes all ad slots on pages containing content about sports. Both of these placements could include the ad slot for the skyscraper ad slot on sports pages. Other placements might include combinations of ad slots appearing in the world news, travel, and weather sections of your site. [Term in DART for Publishers] 
output: Content category A collection of DART sites or zones that are grouped according to a common theme or focus (for example, business or sports). Content categories can be targeted. Content category targeting provides a more horizontal means of targeting, as opposed to the vertical, hierarchical structure of DART site or zone targeting.