 Update semantics is a particular way in which the interpretation-as-process idea can be implemented. The central idea behind update semantics is very simple. We start with a simple model of a hearer/receiver who receives items of information sequentially. At every moment the hearer is in a certain state: she possesses certain information. This state is modified by the incoming information in a systematic way. We now analyze the meaning of the incoming items as their contribution to the change of the information state of the receiver. Thus, meanings are seen as actions, or, more precisely, as action types: They are not the concrete changes of some given state into another, but what such concrete changes have in common.