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

# User

> In Clix, a user is the core entity representing an individual interacting with your mobile application. Clix uniquely identifies and manages users based on how they interact with your service.

## User Types

### Identified User

* An **Identified User** is explicitly identified by a unique `project_user_id` set by your application's own user identification system.
* You can set the `project_user_id` to match the user's ID from your existing system.
* This enables Clix to track, manage, and engage with users consistently across their journey within your application.

### Anonymous User

* An **Anonymous User** does not have a `project_user_id`. This can happen when:
  * The user has not signed in yet.
  * Your service does not implement a user identification system.
* Clix assigns each Anonymous User a unique `anonymous_id`, allowing the system to distinguish each user even without explicit identification.
* Every user, whether identified or anonymous, will always have a unique `anonymous_id`.

## User Identification and Merging

When an Anonymous User becomes an Identified User (for example, upon signing in), Clix attempts to merge the historical activity of the Anonymous User with the newly Identified User. This merging occurs when:

* There are identifiable attributes that match between the anonymous profile and the newly identified profile.
* After merging, all historical activities associated with the `anonymous_id` become associated with the corresponding `project_user_id`.

## Multiple Devices Management

Users often engage with applications on multiple devices. Clix handles this seamlessly by:

* Automatically synchronizing multiple devices to the same user profile.
* Ensuring that all sessions across devices are unified under the same user entity whenever the user starts a session.

This ensures consistent messaging and optimal push notification delivery across all user devices.