Abstract classes in programming are special kinds of classes that cannot be directly instantiated 🚫. Their main purpose is to serve as a blueprint for other classes, providing a common structure and shared functionality. For example, if you have an abstract class `Animal`, it might define methods like `eat()` but not implement them fully. This forces any subclass, such as `Cat` or `Dog`, to provide their own implementations.

The reason abstract classes can't be instantiated is simple: they are meant to be extended. Think of them as incomplete pieces of a puzzle that need more details before they can be used in practice 🧩. By forcing developers to extend these classes, the language ensures that all necessary functionalities are properly defined and implemented.

However, you can create objects from non-abstract subclasses that inherit from an abstract parent class. This way, the abstract class's structure is preserved while allowing flexibility in specific use cases 🎉. Abstract classes play a crucial role in object-oriented design by promoting code reuse and enforcing consistent behavior across related entities.