> For the complete documentation index, see [llms.txt](https://fredhopper.gitbook.io/product-discovery/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://fredhopper.gitbook.io/product-discovery/tracking-and-sending-events/identities/user-object.md).

# User Object

Understand the user object in activity tracking: manage identities, segments, and traits for user identification, analytics, and personalization in your front-end tracking setup.

The user object is part of the [activity object](/product-discovery/tracking-and-sending-events/activities/activity-object.md) and holds all the information needed to identify users.

For example:

```json
"user": {
    "identities": {
        "sessionId": "session-id",
        "eCommerceId": "e-commerce-id",
        "customId1": "custom-id-1",
        "customId2": "custom-id-2"
    },
    "segments": ["segment-1", "segment-2"],
    "traits": {
        "customTrait1": "value",
        "customTrait2": "value"
    }
}
```

The user object is split into three distinct properties:

* **Identities**: Unique identifiers that apply to one user
  * **The session ID is mandatory**. It is a value unique to a session and can be used to identify even anonymous users.
  * Any additional identities, such as an **e-commerce ID**, can be used to identify users across sessions and devices.

{% hint style="info" %}
Session IDs are supported by default. To include additional identities, contact the Rezolve AI team.
{% endhint %}

* **(XO only) Segments**: Labels to qualify groups of users sharing common traits or behaviors, such as "Frequent buyer" or "Prospect"
  * Segments can provide more detailed analytics, better personalization, and better recommendations, but are **optional**.
* **(XO only) Traits**: Various qualifying values related to the user in question, including profile, and preference data, age, gender, likes, etc.
  * Traits can provide more detailed analytics, better personalization, and better recommendations, but are **optional.**

{% hint style="danger" %}
Traits refer to information you know about your users and that you want to use for tracking. **You must only send information relevant to the platform usage and avoid sending personal information**.
{% endhint %}