The "diamond problem" is a term used in computer programming to describe an issue that can occur when multiple classes inherit from a common superclass. The problem arises when two subclasses override a method with different implementations, and a third subclass inherits from both of them.   In this scenario, the subclass will inherit two different implementations of the method, and it is not clear which one should be used. This can lead to errors or unexpected behavior at runtime. The diamond problem can be avoided by using careful design patterns, such as the template method pattern. However, it is still something that programmers need to be aware of when working with inheritance.