Interactive Design

Interactive Design is the process of creating an experience for others allowing them to relate or respond. It is focused on user experience and usability; which is an important part of Interactive Design. Interactivity is about real human engagement thus you must take into account factors from the user's perspective like ease of usability, effectiveness and enjoyment.

"If I were to sum up interaction design in a sentence, I would say that it's about shaping our everyday life through digital artifacts-for work, for play and for entertainment..."

Gillian Crampton Smith

According to Nathan Shedroff, Interactivity can be divided into various spectrums.

References
Crampton Smith, Gillian. "Foreword. Designing Interaction."
Shedroff, Nathan. "A Unified Theory of Design. " Nathan Shedroff's World 1994.