user interface component

  a part of the content that is perceived by users as a single control for a distinct function

  Multiple user interface components may be implemented as a single programmatic element. "Components" here is not tied to programming techniques, but rather to what the user perceives as separate controls.

  User interface components include form elements and links as well as components generated by scripts.

  What is meant by "component" or "user interface component" here is also sometimes called "user interface element".

  An applet has a "control" that can be used to move through content by line or page or random access. Since each of these would need to have a name and be settable independently, they would each be a "user interface component."