User interface

1. the user agent user interface, i.e., the controls (e.g., menus, buttons, prompts, and other components for input and output) and mechanisms (e.g., selection and focus) provided by the user agent ("out of the box") that are not created by content.
   AND
2. the "content user interface," i.e., the enabled elements  that are part of content, such as form controls, links, and applets.

The term "user interface control" refers to a component of the user agent user interface or the content user interface, distinguished where necessary.