A topic criterion. Use topics to target or exclude placements in the Google Display Network based on the category into which the placement falls (for example, "Pets \& Animals/Pets/Dogs").

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v26/common/criteria.proto)

| Fields ||
|---|---|
| ## `path[]` | `string` The category to target or exclude. Each subsequent element in the array describes a more specific sub-category. For example, "Pets \& Animals", "Pets", "Dogs" represents the "Pets \& Animals/Pets/Dogs" category. |
| ## `topic_constant` | `string` The Topic Constant resource name. |