On a network, there are provided a plurality of shared fields enabling a plurality of computers to interact with each other. The computer is allowed to move between the shared fields anytime. Upon leaving a shared field, the computer records, on the network, contexts including identification of another computer relating to the interaction. When participating in another shared field, the user reads out the contexts from the network and reflects them on another interaction held in the latter shared field. Thus, interactions on shared fields act on construction of global fields for interactions.