> [!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/UserIdentifierSourceEnum.UserIdentifierSource).

The type of user identifier source for offline Store Sales, click conversion, and conversion adjustment uploads.

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

| Enums ||
|---|---|
| ## `FIRST_PARTY` | Indicates that the user identifier was provided by the first party (advertiser). |
| ## `THIRD_PARTY` | Indicates that the user identifier was provided by the third party (partner). |
| ## `UNKNOWN` | Used for return value only. Represents value unknown in this version |
| ## `UNSPECIFIED` | Not specified. |