Python is an object-oriented programming language, which means it manipulates programming constructs called objects. You can think of an object as a single data structure that contains data as well as functions; the functions of an object are called its methods. For example, any time you call

len("Eric")

Python is checking to see whether the string object you passed it has a length, and if it does, it returns the value associated with that attribute. When you call

my_dict.items()

Python checks to see if my_dict has an items() method (which all dictionaries have) and executes that method if it finds it.

But what makes "Eric" a string and my_dict a dictionary? The fact that they’re instances of the str and dict classes, respectively. A class is just a way of organizing and producing objects with similar attributes and methods.