||When striving for usable systems, context has been recognised as a vital concept in interaction with technology. The problem with this concept is that it is hard to grasp and notoriously difficult to define. Context has normally been likened with terms like 'situation', 'setting', 'environment', 'surrounding', and so forth. But what is it that distinguishes context from these synonyms? In this talk, I will attempt an exposť of this elusive term to hopefully bring some light onto the matter of how we can begin to define it. The answer, I believe, lies in a dual theory of properties.