Learn how to use dimensions to target available inventory
Inventory Discovery allows you to target available inventory based on dimensions.
To add targeting based on dimensions:
1. Click Marketplace 
2. Navigate to "Filter Inventory" to the right of the interface and select any of the following dimensions:
| Dimension | Description |
|---|---|
| User geography | All targetable regions. Search for a region in the search box at the top or browse through them all. |
| Languages | All targetable languages. |
| Ad position | Choose whether you'd like your results to be limited to Above the fold or Below the fold. |
| User lists | All available user lists associated with your account. To learn more, see Inventory Discovery: Advanced queries. |
| Brand safety exclusions | Site categories the Authorized Buyers blocks by default for new campaigns. Learn more about how to Exclude sensitive or mature topics in your campaigns. |
| Inventory formats | By default, image ad inventory is shown. Check Flash or HTML5 to include these types as well. |
| Creative sizes | Select a few ad sizes to limit the inventory results. See all supported sizes in the Authorized Buyers. |
| Page verticals | Detected page content categories, as passed by detected_vertical in the BidRequest. See the complete list of verticals, and our Bid Response guide for context. |
| Deals | Select one or more Preferred Deals or Private Auctions to see an inventory estimate made available by these deals. To learn more, see Inventory Discovery: Advanced queries. |
| Devices | Narrow your results to specific device platforms: Desktop, Tablet, or Mobile. |
| Demographics | Narrow your results to the demographic groups you'd like to reach, with both age and gender categories. |
| Video context | Choose from a variety of video targeting criteria: Placement: Preroll, Midroll or Postroll. Platform: Whether the video appears on a Game or a Mobile interstitial, for example. |
| Video format | Duration: Choose the length of the ad slot. Format: Whether the video player accepts HTML5, FLash or neither. VPAID: Whether the ad slot is VPAID compatible. |