> [!CAUTION]
> **Caution:** This documentation is for Google Ads API **v24** . The latest active version is [**v26**](https://developers.google.com/google-ads/api/reference/rpc/latest/TopicConstant).

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/v24/resources/topic_constant.proto)

| Fields ||
|---|---|
| ## `id` | `int64` Output only. The ID of the topic. |
| ## `path[]` | `string` Output only. 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. List of available topic categories at <https://developers.google.com/google-ads/api/data/topics> |
| ## `resource_name` | `string` Output only. The resource name of the topic constant. topic constant resource names have the form: `topicConstants/{topic_id}` |
| ## `topic_constant_parent` | `string` Output only. Resource name of parent of the topic constant. |