Magic methods in Python are the special methods that start and end with the double underscores. They are also called dunder methods. Magic methods are not meant to be invoked directly by the user, but happens internally on a certain action.

Built-in classes in Python define many magic (dunder) methods. Use the dir() function to see the number of magic methods inherited by a class. For example, the int class.

print(dir(int))
['__abs__', '__add__', '__and__', '__bool__', '__ceil__', '__class__',
 '__delattr__', '__dir__', '__divmod__', '__doc__', '__eq__',
'__float__', '__floor__', '__floordiv__', '__format__', '__ge__',
'__getattribute__', '__getnewargs__', '__gt__', '__hash__',
'__index__', '__init__', '__init_subclass__', '__int__', '__invert__',
'__le__', '__lshift__', '__lt__', '__mod__', '__mul__', '__ne__',
'__neg__', '__new__', '__or__', '__pos__', '__pow__', '__radd__',
'__rand__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__',
'__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__',
'__round__', '__rpow__', '__rrshift__', '__rshift__', '__rsub__',
'__rtruediv__', '__rxor__', '__setattr__', '__sizeof__', '__str__',
'__sub__', '__subclasshook__', '__truediv__', '__trunc__', '__xor__',
'as_integer_ratio', 'bit_length', 'conjugate', 'denominator',
'from_bytes', 'imag', 'numerator', 'real', 'to_bytes']

print(help(int))
....
too much to show here. try it out.
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print(help(int.__float__))
Help on wrapper_descriptor:

__float__(self, /)
    float(self)

None

print(help(int.__str__))
Help on wrapper_descriptor:

__str__(self, /)
    Return str(self).

None

print(help(str))
....
too much to show here. try it out.
....