According the Castells who made his PHD in the field of interactive documentary first graphical user interface (GUI Graphic User Interface) was a key for the decade that began till today for any interactive application, and especially in the case of the interactive documentary.
“A graphical user interface (GUI), is a type of user interface that allows users to interact with electronic devices through graphical icons and visual indicators such as secondary notation, instead of text-based user interfaces, typed command labels or text navigation.”
Design of the visual appearance and temporal behaviour of a GUI has a pivotal value because that is what enhances the “usability”. Usability is a key principle of designing the efficiency of every type of human -computer interaction. Software programmers and designers find most sufficient methods to create user centred applications.