Python: Understanding classmethod The code I am providing is runnable, just run it in any python interpreter or IDLE and you will see how I mentioned step-by-step flow of program using print() statement. # using built-in classmethod as decorator # classmethod allows changes to class. This change can even be made by classreference and by object reference( Yeah, thnx to this method, it is possible) class Student: no_of_Leaves = 8 def __init__(self,naam,grad,umar): self.name= naam self.grade = grad self.age = umar def printDetails(self): # self refers to the object using it, i.e if harry calls this func self = harry print(f"Name is {self.name} \nGrade is {self.grade} \nAge is {self.age}") @classmethod # 1 . This line has the same function as "change = classmethod(change)" down there. so if you uncomment that one and comment this one # it won't make any difference, but don't uncomment both or you will have to deal with an error def change(cls,modifiedleaves): cls.no_of_Leaves = modifiedleaves # change = classmethod(change) harry = Student("harry",10,21) # let's see how class method works print("checking initial value of leaves: ")# checking initial value of leaves print("Value of leaves in Student:",Student.no_of_Leaves,"-------Harry leaves: ",harry.no_of_Leaves) # prints 8 print("\nlet's try changing it using class reference") # changing class variable value using class-reference "Student.no_of_leaves" Student.no_of_Leaves = 10 print("\nafter changing it \nValue of leaves in Student:",Student.no_of_Leaves,"-------Harry leaves: ",harry.no_of_Leaves) print("\nlet's try changing it using object(harry) reference") harry.no_of_Leaves = 12 print("\nafter changing it \nValue of leaves in Student:",Student.no_of_Leaves,"-------Harry leaves: ",harry.no_of_Leaves) print("\n See the difference? You can't change class variable value using object that's why a new instance variable was created for harry having leaves: 12") print("___________________________________________________________________________________________________________________________________________________") print("""\nNow, let's see the Power of classmethod, but first, let me delete that instance variable with no_of_leaves 12____ so that' we have a clear" "understanding of what is happening""") print("\nBefore deleting instance variable \nValue of leaves in Student:",Student.no_of_Leaves,"-------Harry leaves: ",harry.no_of_Leaves) del harry.no_of_Leaves print("\nAfter deleting instance variable \nValue of leaves in Student:",Student.no_of_Leaves,"-------Harry leaves: ",harry.no_of_Leaves) print("See? Back to 10 and 10") print("\nLet's Try changing it using classmethod while calling it using class \"Student\" " ) Student.change(12) print("\nafter changing it \nValue of leaves in Student:",Student.no_of_Leaves,"-------Harry leaves: ",harry.no_of_Leaves) print("\nLet's Try changing it using classmethod while calling it using object \"harry\" " ) harry.change((14)) print("\nafter changing it \nValue of leaves in Student:",Student.no_of_Leaves,"-------Harry leaves: ",harry.no_of_Leaves) print("""\nSee the power of classmethod? Above, while directly trying to change it using object(harry) a new variable was created, but now, it managed to modify the existing class variable so that's why class method is useful""")