There are two broad categories of targeting—hierarchical and flat. Hierarchical targeting allows you to target a higher-level value, which also automatically targets all "children" or lower-level values below it. The other type of targeting is flat targeting. This kind of targeting allows you to include only a single value itself. Targeting a flat value does not automatically or implicitly target anything else.
For example, all the values under the Geography targeting type are hierarchical. You can target United States, which targets the set of all its lower-level values, including all the states and cities in the United States. You could also drill down and target the U.S. state of New York, for instance, which targets the set of all of that state's lower-level values, including New York City, Albany, Rochester, and so forth.
In contrast, all the values under the targeting type Connection are flat. You can only include single values themselves and not any "parents". For example, under the Connection targeting type, if you can click Mobile carrier, you can find T-Mobile. Under T-Mobile, if you drill through, you can find various values to target, such as T-Mobile Australia and T-Mobile United Kingdom. You can target any or all of the individual values under T-Mobile. However, you cannot target the mobile carrier T-Mobile in order to target the values below it. You must select all of the individual values under it instead.
Other flat targeting includes most of the targeting classes under the Device targeting type: Device category, Device capability, Browser, and Browser language, Operating system—with the noted exceptions for operating systems being Android, Apple iOS, which are hierarchical. Hierarchical targeting includes Manufacturer/device (under the Device targeting type), and all targeting groups under the Inventory and Geography targeting types.
Flat targeting
- Device category
- Device capability
- Browser
- Browser language
- Operating system (except Android, and Apple iOS)
Hierarchical targeting
- Android, and Apple iOS operating systems
- Geography
- Manufacturer/device
- Inventory