Final answer:
Refactoring aims to improve the structure of code to produce clean code, which is easy to understand and maintain.
Step-by-step explanation:
Refactoring is a programming process used to restructure existing computer code without changing its external behavior, aiming to improve nonfunctional attributes of the software. The goal of refactoring is to produce clean code, which is code that is easy to understand and maintain. The correct answer to the fill-in-the-blank question is: Refactoring is used to create clean code, which is code that is written in a way that is readable and makes its purpose clear.