1. A system for supporting an arbitrary activity involving collaborators, the system comprising: a processor which has access to a representation of a model of the activity, the form of the model being defined by the collaborators and the representation providing access to information relating to the activity; and an interface to the system for the collaborators, the interface being provided by the processor and the interface permitting a collaborator to perceive and modify the model's form and to perceive and modify the information to which the representation of the model provides access.