> ## Documentation Index
> Fetch the complete documentation index at: https://formbricks.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# User Identification

> User Identification helps you to not only segment your users but also to see more information about the user who responded to a survey. This helps you to target surveys to specific user segments and see more information about the user who responded to a survey.

<Note>
  User identification is part of the Formbricks [Enterprise Edition](/self-hosting/advanced/license).
</Note>

### Understanding Identified vs Unidentified Users

In Formbricks, understanding the difference between identified and unidentified users is crucial for effective survey segmentation and targeted feedback collection.

| Feature                                                  | Unidentified Users | Identified Users |
| -------------------------------------------------------- | ------------------ | ---------------- |
| Show surveys based on **trigger** actions                | ✅                  | ✅                |
| Set **recontact details** to avoid survey fatique        | ✅                  | ✅                |
| Target a subset of users using **attributes & segments** | ❌                  | ✅                |
| Collect **user information** in Formbricks               | ❌                  | ✅                |
| Track **custom attributes**                              | ❌                  | ✅                |
| Counts towards your **monthly tacked user (MTU)** limit  | ❌                  | ✅                |
| Recommended for **public-facing websites**               | ✅                  | ❌                |
| Recommended for **web apps after login**                 | ❌                  | ✅                |

## Identified Users

Identified users are those for whom specific information has been set, notably the userId. This identification allows for more precise targeting of surveys and a deeper understanding of the feedback provided. When enabled, all information specified by you and all actions are sent to Formbricks.

This method is recommended for applications where users are required to log in and will often return.

### Setting User ID

To enable user identification, call the `setUserId` function of Formbricks and pass the user id. The user will show up in the Formbricks dashboard. Use a unique string, like a database ID or a unique email address. You can also anonymize the identifier, as long as it is unique for each user.

```javascript theme={null}
formbricks.setUserId("<user-id>");
```

## Setting Custom User Attributes

Use the `setAttribute` function to set custom attributes for the user (e.g., name, plan).

```javascript Setting Custom Attributes theme={null}
formbricks.setAttribute("Plan", "free");
```

The `setAttribute` function works like this:

```javascript Setting Custom Attributes theme={null}
formbricks.setAttribute("attribute_key", "attribute_value");
```

You can also set multiple attributes at once by passing an object to the `setAttributes` function:

```javascript Setting Multiple Custom Attributes theme={null}
formbricks.setAttributes({
  attribute_key_1: "attribute_value_1",
  attribute_key_2: "attribute_value_2",
});
```

<Note>
  **Note**: the number of different attribute classes (e.g., "Plan," "First Name," etc.) is currently limited
  to 150 attributes per environment.
</Note>

### Setting User Language

Use the `setLanguage` function to set the user's preferred language for surveys. This allows you to display surveys in the user's language when multi-language surveys are enabled. You can pass either the ISO language code (e.g., "de", "fr", "es") or the language alias you configured in your project settings.

```javascript Setting User Language theme={null}
formbricks.setLanguage("de"); // ISO identifier or Alias set when creating language
```

### Logging Out Users

When a user logs out of your webpage, also log them out of Formbricks to prevent activity from being linked to the wrong user. Use the logout function:

```javascript Logging out User theme={null}
formbricks.logout();
```