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

# User Id - User Property

Dittofeed uses the `id` property to identify logged in users. The `id` value is provided by you, the developer emitting events. This is a special user property in that only 1 user property can exist of this type, and it can not be deleted or modified.