Objects

Typically an object is an instance of class. An object is “anything with a boundary.” This can be extended as “anything with a boundary that represents a uniquely identifiable entity; unit; or item, real or abstract; that represents some element in the problem domain.” An object is capable of passing messages to other objects and also receiving messages and processing the data of a class.
Objects are strongly tied up with the idea of encapsulation, which is broadly the practice of bringing together elements to produce a new entity. In the more specific case of object-orientated programming, encapsulation implies data hiding and the abstraction of behaviour from implementation: if the internal data and workings of the object are encapsulated, then objects have to interact through a set of clearly defined interfaces.