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.