Moreover, control theory offers a broad view of interaction; itis not limited to input.

Interaction is understood as actions and reactions that minimize the discrepancybetween the present state and the goal state.

All theories of interaction discussed in this part assume intentionality: People have goalsthat have a (mutually) causal role in interaction.

One type of determination is shared by all theories of interaction in HCI: teleological determina-tion.

What happens in interaction is mutually determined by the human and the computer. In other words, what happens in interaction cannot be attributed solely to the human or the computer—the two must be considered together.

By now, it should be clear that the term interaction covers a lot of ground in human–computerinteraction (HCI).

Phenomena in interaction are emergent, that is, they are not attributable to the user or to the computer alone.

Interaction is a dynamic phenomenon that unfolds over time as users and computers influence each other.

What happens in interaction cannot be attributed solely to the human or the computer—the two must be considered together.

Moreover, interaction takes place at dif-ferent timescales.

Interaction is a core notion in HCI and refers to the mutual influence between people and computers.

Ithasbeenusedtodescribeindividuals,groups,andcommunitiesusingcomputers.