[DOCS-14565] Document anonymous_id for RUM and Product Analytics

content/en/product_analytics/data_collected.md

@@ -22,7 +22,7 @@ Product Analytics collects user activity data as events. Each event has two type
 
 Every event includes the [default attributes](#default-attributes). Each event type also has [specific telemetry and attributes](#event-specific-attributes).
 
-To identify individual users across sessions, Product Analytics relies on the `usr.id` and `usr.email` attributes.
+To identify individual users across sessions, Product Analytics relies on the `usr.id` and `usr.email` attributes. For unauthenticated users or visitors who never log in, the RUM SDK automatically assigns a `usr.anonymous_id` to track activity. See [Track unauthenticated users][4] for details.
 
 <div class="alert alert-info">Product Analytics uses the same SDKs and configuration as Real User Monitoring (RUM) to collect data. Unlike RUM, Product Analytics does not collect Errors, Resources, Long Tasks, or Vitals events. For the full list of RUM event types and attributes, see the data collected pages for <a href="/real_user_monitoring/application_monitoring/browser/data_collected/">browser</a>, <a href="/real_user_monitoring/application_monitoring/ios/data_collected/">iOS</a>, and <a href="/real_user_monitoring/application_monitoring/android/data_collected/">Android</a>.</div>
 
@@ -88,6 +88,7 @@ You can enable [tracking user info][3] globally to collect and apply user attrib
 | `usr.id` | string | Identifier of the user. |
 | `usr.name` | string | Name of the user. |
 | `usr.email` | string | Email of the user. |
+| `usr.anonymous_id` | string | Randomly generated UUID assigned to unauthenticated users. Persists for up to one year. See [Track unauthenticated users][4]. |
 
 ## Event-specific attributes
 
@@ -172,3 +173,4 @@ The following attributes are specific to each event type.
 [1]: /product_analytics/guide/action_management/
 [2]: https://app.datadoghq.com/rum/list
 [3]: /real_user_monitoring/application_monitoring/browser/advanced_configuration/#user-session
+[4]: /real_user_monitoring/application_monitoring/browser/advanced_configuration/#track-unauthenticated-users

content/en/product_analytics/profiles.md

@@ -21,6 +21,8 @@ User and account profiles are generated from RUM events collected through the RU
 
 User profiles are grouped by the `user_id` attribute, while account profiles are grouped by `account_id`.
 
+For unauthenticated users or visitors who never call `setUser`, the RUM SDK automatically tracks activity using `usr.anonymous_id`. See [Track unauthenticated users][9] for details.
+
 You can also customize these pages by adding attributes that matter most to your team. See the [Custom Attributes section](#use-custom-attributes-to-enrich-profiles) to learn how to tailor profile data to your needs.
 
 
@@ -188,3 +190,4 @@ You can filter these custom attributes throughout the product analytics platform
 [6]: https://app.datadoghq.com/product-analytics/segments
 [7]: https://app.datadoghq.com/product-analytics/profiles
 [8]: https://app.datadoghq.com/product-analytics/profiles/accounts
+[9]: /real_user_monitoring/application_monitoring/browser/advanced_configuration/#track-unauthenticated-users

content/en/real_user_monitoring/application_monitoring/browser/advanced_configuration.mdoc.md

@@ -1,6 +1,6 @@
 ---
 title: Advanced Configuration
-description: "Configure RUM Browser SDK to modify data collection, override view names, manage user sessions, and control sampling for your application's needs."
+description: "Configure RUM Browser SDK to modify data collection, override view names, manage user sessions, track unauthenticated users, and control sampling for your application's needs."
 aliases:
   - /real_user_monitoring/installation/advanced_configuration/
   - /real_user_monitoring/browser/modifying_data_and_context/
@@ -885,6 +885,21 @@ window.DD_RUM && window.DD_RUM.clearUser()
 ```
 {% /if %}
 
+### Track unauthenticated users
+
+For unauthenticated visitors or users who have not yet logged in, the RUM SDK automatically tracks activity using `usr.anonymous_id`. This lets you analyze user behavior without requiring authentication.
+
+`usr.anonymous_id` is a randomly generated UUID (v4). It is not derived from any user PII, IP address, device fingerprint, or hardware identifier.
+
+The ID has the following properties:
+
+- **Lifetime**: Persists for up to one year across sessions in the Datadog session cookie (`_dd_s_v2`).
+- **Scope**: Per-browser and per-domain. Incognito mode, cookie clearing, or switching browsers or devices produces a new `anonymous_id`.
+
+The ID resets if the user revokes tracking consent with `setTrackingConsent('not-granted')` or clears cookies.
+
+**Note**: `usr.anonymous_id` is enabled by default. To disable it, set [`trackAnonymousUser: false`](https://datadoghq.dev/browser-sdk/interfaces/_datadog_browser-rum.RumInitConfiguration.html#trackanonymoususer) in your `init` config.
+
 ## Account
 
 To group users into different set, use the account concept.