Metaclasses in Python are a powerful and advanced feature that allows developers to customize class creation. Essentially, a metaclass is a “class of a class,” defining how classes themselves are constructed, similar to how classes define the behavior of their instances. In Python, everything is an object, including classes, which are instances of metaclasses. The default metaclass in Python is type, which is automatically used when defining a class. Understanding metaclasses can unlock new possibilities for metaprogramming and dynamic code generation, making them an essential concept for advanced Python developers to grasp.