  Context and context-awareness provides computing environments with the
ability to usefully adapt the services or information they provide. It is the
ability to implicitly sense and automatically derive the user needs that
separates context-aware applications from traditionally designed applications,
and this makes them more attentive, responsive, and aware of their user's
identity, and their user's environment. This paper argues that context-aware
applications capable of supporting complex, cognitive activities can be built
from a model of context called Activity-Centric Context. A conceptual model of
Activity-Centric context is presented. The model is illustrated via a detailed
example.
