|1||A pen||The upper 37% of the pen|
|2||A computer keyboard||The air above the keyboard|
|3||A shoe||The color of the shoe|
|4||A mouse||The sound of a mouse click|
It is easier to list things that are objects than to list things that are not objects. Just to talk about something seems to make it an object, somehow. René Descartes (the 17th century philosopher) observed that humans view the world in object-oriented terms. The human brain wants to think about objects, and our thoughts and memories are organized into objects and their relationships. Perhaps non-human brains work differently.
One of the ideas of object-oriented software is to organize software in a way that matches the thinking style of our object-oriented brains. Instead of machine instructions that change bit patterns in main storage, we want objects that have properties and interact with other objects. Of course, at the machine level nothing has changed — bit patterns are being manipulated by machine instructions. But we don't have to think that way.
Look at my list of objects and your own list and try to describe what all objects have in common.