How device Id works on mixpanel

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In Mixpanel, the device ID plays a crucial role in user identification and tracking. Here's how it works:

1. Automatic Generation: The device ID, represented as $device_id, is automatically generated by Mixpanel's client-side SDKs for each unique device or browser.

2. Anonymous User Identification: When a user is anonymous (not logged in), the $device_id serves as the primary identifier for that user. It's used to track events and associate them with a specific device or browser session.

3. Event Association: All client-side events sent to Mixpanel include the $device_id property. This allows Mixpanel to associate events with a particular device even if the user is not identified.

4. Identity Merging: When a user logs in or is identified, Mixpanel uses the $device_id along with the $user_id to create an identity cluster. This process links the anonymous activity (tracked with $device_id) to the identified user.

5. Persistence: The $device_id persists across sessions until it's reset (usually when a user logs out) or the app is uninstalled and reinstalled.

6. Reset Functionality: When you call the .reset() method (e.g., during user logout), it generates a new $device_id for the session, ensuring that multiple users on the same device are not incorrectly considered as a single user.

It's important to note that the exact behavior might vary slightly depending on whether you're using the Simplified or Original ID Merge system in Mixpanel.

For more detailed information, you can refer to the following resources: - Identifying Users (Simplified) - Understanding Simplified ID Merge

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