Refactoring is a methodical approach involving the internal transformation of a system's structure without modifying its external function or characteristics. As an academic concept and research area, it investigates systematic techniques for analyzing, identifying, and applying changes to internal components or processes to enhance intrinsic qualities such as efficiency, clarity, and maintainability. Its key characteristics include the preservation of external behavior, the application of controlled, incremental transformations, and a focus on optimizing internal structure. The significance lies in improving system robustness, facilitating future development and evolution, and reducing accumulated technical debt.