In this chapter, you've learned that
An object is a software abstraction of a physical or conceptual real-world object.
A class serves as a template for defining objects: specifically, a class defines the following:
What data the object will house, known as an object's attributes
An object may then be thought of as a filled-in template.
Just as we can declare variables to be of simple predefined types such as int, double, and bool, we can also declare variables to be of user-defined types such as Student and Professor.
When we create a new object (a process known as instantiation), we typically store a reference to that object in a reference variable. We can then use that "handle" to communicate with the object.
We can define attributes of a class A to serve as handles on objects belonging to another class B. In doing so, we allow each object to encapsulate the information that rightfully belongs to that object, but enable objects to share information by contacting one another whenever necessary.