Which placement types require a creative in order to generate placement tags?

In-banner placements require a creative to generate placement tags because they are designed to display visual advertisements directly within a web page's content. The creative (image, HTML5, etc.) is the actual ad content that the user sees, and the placement tag includes the necessary code to render this creative. In-stream video placements, while displaying video ads, often rely on VAST/VPAID tags which point to the video content hosted elsewhere, rather than embedding the video creative directly within the placement tag itself. Tracking placements are solely for monitoring impressions or clicks and do not display any visual content, therefore they do not require a creative.