Of this abstraction. The values for getRadius() or getCircumference() in the above mentioned case in point may be stored directly, or they could be calculated, it would not issue to the caller; the setters could possibly or might not have Unintended effects; it will not subject to your caller. See https://propertyingurugram.in/integrated-business-model-in-real-estate-gives-m3m-operational-advantage/