What makes a class abstract in programming?

A class is considered abstract in programming when it contains at least one abstract method. An abstract method is a method that is declared without an implementation. This means that subclasses inheriting from the abstract class are required to provide concrete implementations for these abstract methods. This design enforces a contract for the subclasses, ensuring that they all adhere to a consistent interface, while allowing flexibility in how the specific functionality is implemented.

This characteristic is crucial because abstract classes are often used in object-oriented programming to define common behavior while leaving the implementation details to the subclasses. By utilizing abstract classes, developers can create a more organized and modular architecture within their applications, allowing for easier maintenance and scalability.