Dey, A. Understanding and Using Context. Personal and Ubiquitous Computing, Vol. 5, No. 1. (20 February 2001), pp. 4-7. [PDF]
This work builds on previous studies of contextual applications and proposes to define what context is a what context-aware applications are. The author refer to the work of Schilit and Theimer (1994) where context is referred to as location, identities of nearby people and objects, and changes to those objects. A later definition of Schilit , Adams, and Want (1994) and the definition of Pascoe (1998) defines the important aspects of context, which are: where you are, who you are with, and what resources are nearby.
The author consider these definitions as too generic and presents his own: “Context is any information that can be used to characterise the situation of an entity, place, or object that is considered relevant to the interaction between a user and an application, including the user and applications themselves.“
Subsequently, the author defines context-aware applications as: “A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user’s task.” According to the author, there are three categories of features that a context aware application can support: a) presentation of information and services to a user; b) automatic execution of a service for a user; c) tagging of context to information to support later retrieval.
As a last contribution, the paper introduces the situation abstraction, which is an aggregated description of the states of relevant entities.