> [!CAUTION]
> **Caution:** This documentation is for Google Ads API **v23** . The latest active version is [**v26**](https://developers.google.com/google-ads/api/reference/rpc/latest/BiddingSourceEnum.BiddingSource).

Indicates where a bid or target is defined. For example, an ad group criterion may define a cpc bid directly, or it can inherit its cpc bid from the ad group.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v23/enums/bidding_source.proto)

| Enums ||
|---|---|
| ## `AD_GROUP` | The bid or target is defined on the ad group. |
| ## `AD_GROUP_CRITERION` | The bid or target is defined on the ad group criterion. |
| ## `CAMPAIGN_BIDDING_STRATEGY` | Effective bid or target is inherited from campaign bidding strategy. |
| ## `UNKNOWN` | Used for return value only. Represents value unknown in this version. |
| ## `UNSPECIFIED` | Not specified. |