Python: Essential Reference, Third Edition

Terminology

Every piece of data stored in a program is an object. Each object has an identity, a type, and a value.

For example, when you write a = 42, an integer object is created with the value of 42. You can view the identity of an object as a pointer to its location in memory. a is a name that refers to this specific location.

The type of an object (which is itself a special kind of object) describes the internal representation of the object as well as the methods and operations that it supports. When an object of a particular type is created, that object is sometimes called an instance of that type. After an object is created, its identity and type cannot be changed. If an object’s value can be modified, the object is said to be mutable ...