What is Python ABC Module?

The abc module provides infrastructure for defining abstract base classes in Python. Classes inheriting from ABC with methods decorated with @abstractmethod cannot be instantiated directly — subclasses must implement all abstract methods. This enforces interface contracts at instantiation time rather than at method call time. ABCs are used extensively in Python's standard library: collections.abc defines Iterable, Mapping, Sequence interfaces. Custom ABCs enable type checking with isinstance() and designing frameworks where plugins must implement specific methods. The __subclasshook__ method allows virtual subclass registration without actual inheritance.