Python: What are descriptors and how do they relate to decorators?

1class Validated:
2    def __init__(self, min_val=None, max_val=None):
3        self.min_val = min_val
4        self.max_val = max_val
5
6    def __set_name__(self, owner, name):
7        self.name = name
8
9    def __get__(self, obj, objtype=None):
10        if obj is None:
11            return self
12        return obj.__dict__.get(self.name)
13
14    def __set__(self, obj, value):
15        if self.min_val is not None and value < self.min_val:
16            raise ValueError(f"{self.name} must be >= {self.min_val}")
17        if self.max_val is not None and value > self.max_val:
18            raise ValueError(f"{self.name} must be <= {self.max_val}")
19        obj.__dict__[self.name] = value
20
21class Product:
22    price = Validated(min_val=0)
23    quantity = Validated(min_val=0, max_val=1000)
24
25p = Product()
26p.price = 100   # OK
27# p.price = -10  # ValueError!