In the fields of information science, communication, and industrial design, there is debate over the meaning of Interactivity. In the "contingency view" of interactivity, there are three levels: Noninteractive, when a message is not related to previous messages; Reactive, when a message is related only to one immediately previous message; and Interactive, when a message is related to a number of previous messages and to the relationship between them.[1] Interactivity is similar to the degree of responsiveness, and is examined as a communication process in which each message is related to the previous messages exchanged, and to the relation of those messages to the messages preceding them. Contents Human communication is the basic example of interactive communication in which it involves in two different things; human to human interactivity and human to computer interactivity. Human-Human interactivity is the communication between people and people. On the other hand, human to computer communication is the way that people communicate through new media. According to Rada Roy (1996) stated that "Human Computer interaction model might consists of 4 main components which are consisted of HUMAN, COMPUTER, TASK ENVIRONMENT and Machine ENVIRONMENT. The two basic flows of information and control are assumed. The communication between people and computers; one must understand something about both and about the tasks which people perform with computers. A general model of human - computer interface emphazizes the flow of information and control at the human computer interface (12)." Human to Human interactivity, there are consisted of many conceptualizations which based on anthropomorphic definitions. For example, complex systems that detect and react to human behavior are sometimes called interactive. Under this perspective, interaction includes responses to human physical manipulation like movement, body language, and/or changes in psychological states. In the context of communication between a human and an artifact, interactivity refers to the artifact’s interactive behaviour as experienced by the human user. This is different from other aspects of the artifact such as its visual appearance, its internal working, and the meaning of the signs it might mediate. For example, the interactivity of an iPod is not its physical shape and colour (its so-called "design"), its ability to play music, or its storage capacity—it is the behaviour of its user interface as experienced by its user. This includes the way you move your finger on its input wheel, the way this allows you to select a tune in the playlist, and the way you control the volume. An artifact’s interactivity is best perceived through use. A bystander can imagine how it would be like to use an artifact by watching others use it, but it is only through actual use that its interactivity is fully experienced and "felt". This is due to the kinesthetic nature of the interactive experience. It is similar to the difference between watching someone drive a car and actually driving it. It is only through driving the car that you can experience and "feel" how this car differs from other cars. New Media academic Vincent Maher defines interactivity as "the relation constituted by a symbolic interface between its referential, objective functionality and the subject."[2] The term "look and feel" is often used to refer to the specifics of a computer system's user interface. Using this as a metaphor, the "look" refers to its visual design, while the "feel" refers to its interactivity. Indirectly this can be regarded as an informal definition of interactivity. A more detailed discussion of how interactivity has been conceptualized in the human-computer interaction literature, and how the phenomenology of the French philosopher Merleau-Ponty can shed light on the user experience, see (Svanaes 2000). In computer science, interactive refers to software which accepts and responds to input from humans—for example, data or commands. Interactive software includes most popular programs, such as word processors or spreadsheet applications. By comparison, noninteractive programs operate without human contact; examples of these include compilers and batch processing applications. If the response is complex enough it is said that the system is conducting social interaction and some systems try to achieve this through the implementation of social interfaces. Also, there is the notion of kinds of user interaction, like the Rich UI. New media is an expanding term that encompasses all new technologies we have today. Interactivity is seen as a key association with new media as it basically sets apart the 'old' and new medias. Old media could only offer a sit-back type interaction, whereas new media is much more engaging to their audiences. Technologies such as DVD's and digital TV are classic examples of interactive media devices, where a user can control what they watch and when. However, the Internet has become the prime model of an interactive system. Users can become fully immersed in their experiences by viewing material, commenting it and then actively contributing to it. McMillan (2005) states that interactivity can occur at many different levels and degrees of engagement and that it is important to differentiate between these levels. Use-to-user interaction via the internet; para-social interaction, where new forms of media are generated online; and user-to-system interactivity which is the way devices can be engaged with by a user. Lev Manovich (2001) also makes a clear definition of what interactivity means for the user. He refers to 'open interactivity' as actions such as computer programming and developing media systems, whereas 'closed interactivity' is merely where the elements of access are determined by the user. This definition is part of his principle of variability (one of Manovich's key features of new media). Interactivity also relates to new media art technologies where humans and animals are able to interact with and change the course of an artwork. Artists and researchers around the world are working on unique interfaces to allow new forms of interaction that extend beyond the QWERTY keyboard and the now ubiquitous mouse. Artists, such as Stelarc work to define new interfaces that challenge our notion of what is possible when interacting with machines. His Hexapod for example looks like an insect though walks like a dog and the locomotion is controlled by shifting the body weight and turning the torso. Others like Ken Rinaldo have defined unique interfaces for fish in which Siamese Fighting Fish are able to control their rolling robotic fish bowls to interact across the gap of the glass. Simon Penny's Petit Mal allows a two wheeled sculpture to sense and respond to human presence and intelligently navigate the environment. Denis McQuail mentions interactivity as one of the main characteristic of the new media. He quotes[3]: Interactivity: as indicated by the ratio of response or initiative on the part of the user to the "offer" of the source/sender Various authoring tools are available for creating various kinds of interactivities. Some of the most common platform for creating interactivity includes Adobe Flash and lately released Microsoft Silverlight. The most commonly used authoring tools for creating interactivities include the Harbinger's Raptivity and Articulate's Engage. eLearning makes use of a concept called as interaction model. Using an interaction model any person can create interactivities in a very short period of time. Some of the interation models present with authoring tools fall under various categories like games, puzzles, simulation tools, presentation tools,..etc which can be completely customized.