• Class: A class is a real or a virtual entity that has relevance to the problem at hand and has sharp physical boundaries.
• Object: An object is an instance of a class.
• Encapsulation: The clubbing together of the data and the functions that operate on the data is called encapsulation.
• Inheritance: The art of dividing the class into subclass(es) is inheritance.
• Operator overloading: Operator overloading, in general, means using the same operator in more than one way.
• Function overloading: This means having more than one function with the same name in a class with different arguments.
• A class in Python can be sub-classed.
• Multiple inheritance is also supported in Python. 
• Method overriding is also allowed in Python.
• Classes can be created at runtime and can even be changed at runtime.
• In a class all data members are public in nature so they can be accessed anywhere in the program.

A class can be defined using the class keyword. The class keyword is followed by the name of the class. The body of the class follows:

Syntax

class <name of the class>: def <function name>(<arguments>): ... <members>

Example:

class employee:
  def getdata(self):
    self.name=input('Enter name\t:')
    self.age=input('Enter age\t:')
  def putdata(self):
    print('Name\t:',self.name)
    print('Age\t:',self.age)
e1=employee()
e1.getdata()
e1.putdata()

Definition: Instance variable and class variable

An instance variable is one which is unique to each instance and a class variable is one which is shared by all instances.