Frameworks in iOS development are modular, reusable packages of code and resources that provide specific functionality to applications. They offer a hierarchical structure containing compiled code, header files, resources like images and localization files, and often documentation. iOS provides numerous built-in frameworks such as UIKit for user interface elements, Foundation for fundamental data types and collections, and Core Data for data management. These frameworks form the backbone of iOS app development, offering standardized and optimized implementations of common functionalities. Third-party frameworks extend this ecosystem, providing additional features and tools. Frameworks can be static or dynamic, with dynamic frameworks offering more flexibility in terms of memory usage and updates. The use of frameworks promotes code reuse, maintains consistency across projects, and often improves development efficiency. Effective utilization of both system and third-party frameworks is crucial for building robust, feature-rich iOS applications while minimizing development time and effort.