Interactivity defines a relationship between two actors, whereby both actors play a role in determining system outcomes. There must be some degree of indeterminacy embraced by the system in order for it to produce an interactive experience. For example, A users journey through a website interface is indeterminate in terms of when or where or how the interaction will occur. The interaction, once it happens, will cause the program to respond, and change the state of the relationship. Interactivity is this result of a system which is capable of resolving indeterminate factors in a relationship between two actors.