The data types which are created by the programmers are called 'user-defined' data types. For example, an array, a class, or a module is user-defined data types. We will discuss about these data types later.
We should also remember that Python is a case sensitive programming language. It means capital letters and small letters are identified separately by Python.
For example, the names 'num' and 'Num' are treated as different names and hence represent different variables.