An inclusive definition for interactive media is illusive if not impossible to write. Interactivity in media can be described by degree, but not by a single, all-encompassing definition. Interactive media has been called a "hybrid media technology" because it can combine any format (print, web, disc, video, audio, virtual reality scene, PDF, web link, etc.) that allow users to respond to content.
Inteactive media is evolving at a faster rate than most other aspects of new technology and multisensory experimentation is bringing startling new considerations into the multimedia mix. Movies an audience can taste, touch, see, hear and feel are not science fiction. User created content on Youtube is a manifestation of people's thirst for interactivity, as that web site gives users ultimate control over content by allowing them to create it themselves.
It's not just access that makes multimedia powerful, but the control over content given to users. Interactive Media authoring programs enable the user to manipulate the materials through linking, sorting, searching and annotating activities.