Interacting with Computers
PHILIP G. BARKER · 1987
The world around us consists of a vast collection of objects. Some of these (for example, a computer or a motor car) will be man-made while others (such as a flower or an animal) will exist purely as a consequence of natural evolutionary processes. Some items will exist in a concrete form that enables us to reach out and touch them, whereas many others (such as thoughts and ideas) may be quite abstract. An object may be loosely defined as ‘anything that exists’ — either permanently in the real world or transiently within our imagination or thought processes. As we have suggested above, objects may be of a number of different types and possess widely different properties. Three convenient categories into which objects are often classified are: concrete, abstract, and notional. A book is an example of a concrete object while an idea, a thought or a belief may each be considered to be examples of abstract objects. Similarly, a county or a state is an example of a notional object since the borders that define its actual physical extent could at any time be changed. Likewise, a taxonomy of knowledge is again an example of a notional concept or object. Frequently, the term ‘entity’ is used as a synonym for the word ‘object’.