What does 'refactoring' mean in programming?

Refactoring in programming refers to the process of restructuring existing code without changing its external behavior. This means you can reorganize, simplify, or improve the structure and readability of the code while ensuring that the functionality remains the same from the user's or other systems' perspective.

The goal of refactoring is to make the code easier to understand, maintain, and extend in the future. For example, a developer might rename variables for clarity, break down large functions into smaller ones, or eliminate duplicate code. These changes improve the overall quality of the codebase, but they do not impact how the code behaves when executed.

In contrast, rewriting software from scratch typically involves starting over entirely with a new codebase, which can lead to significant changes in behavior. Testing software functionality adds different variables or conditions to assess how the software responds but does not alter the code structure itself. Finally, optimizing the performance of algorithms is focused on improving execution efficiency rather than reorganizing the code for clarity or maintainability.