The Userreference field stores the uid of a related user. The name of the related user is usually displayed as the value of this field.

The Userreference field can use an autocomplete widget, or, when used with Optionwidgets , the available values can be presented to the end user in a drop-down select list, checkboxes, or radios.

A Userreference field can be used in Views to create a Relationship to a user, to allow you to use any field, argument, or filter from the related user in your view.