What are class methods, static methods, and instance methods?

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Python classes support three styles of callable members. They differ in what (if anything) gets passed implicitly as the first argument. Instance method — the default. Receives the instance as self . Operates on per-object state. Class method — decorated with @classmethod . Receives the class as cls . Operates on the class itself or builds instances via alternative constructors. Static method — decorated with @staticmethod . Receives nothing implicit. Logically belongs to the class but doesn’t use self or cls . Example: class Pizza: def __init__(self, toppings): self.toppings = list(toppings) def describe(self): # instance method return f"pizza with {self.toppings}" @classmethod def margherita(cls): # class method — alternative constructor return cls(["tomato", "mozzarella", "basil"]) @staticmethod def is_vegetarian(toppings): # static method — pure helper return all(t not in {"pepperoni", "bacon"} for t in toppings) p = Pizza.margherita() # uses classmethod constructor p.describe() # instance method Pizza.is_vegetarian(["mushroom"]) # static helper The factory method pattern (from_string) is the most practical use of @classmethod. Know that @staticmethod is just a namespaced function — no access to self or cls. The self vs cls distinction (instance vs class access) is the core concept.