Encapsulation

From the point of view of another object the only knowable features of a software object are those of its interfaces or interfaces; that is its properties, methods and events.

Everything else is hidden or encapsulated. The complexity of the actual implementation is not exposed.

This simplification by hiding reduces complexity and unexpected side effects and also a simple definition of an object to exist.

Encapsulation gives to an abstract object some of the attributes also found in physical objects.

This slight similarity to physical objects has given rise to terms such as ‘software engineering’ suggesting that software objects can be engineered or are physical in some way. However the correct phrase would that software objects can simulate only some of attributes of the physical objects in a computer system in a better way and cannot become physical objects them selves.  Essentially programmatic objects are selected ‘aspects’ of a physical object rather than a complete representation.