Extendable frameworks are software structures designed to allow developers to add new features or functionalities without altering the core system. This flexibility enables easier updates and customization, making it simpler to adapt to changing requirements or integrate new technologies. These frameworks often provide a set of predefined components and tools, which can be extended through plugins or modules. Examples include popular frameworks like Django for web development and React for building user interfaces. By using extendable frameworks, developers can save time and effort while maintaining a robust and scalable application architecture.