What are common code smells and how do you address them?

Code smells indicate potential problems: Long Method (extract methods), Large Class (split responsibilities), Duplicated Code (extract common code), Long Parameter List (introduce parameter object), Feature Envy (move method to appropriate class), Data Clumps (create class for related data), Primitive Obsession (create value objects), Divergent Change (separate concerns), Shotgun Surgery (consolidate related changes). Address through refactoring. Use static analysis tools (SonarQube, ESLint) to detect smells automatically.