Refactoring is like tidying up software to make it better. A study looked at changes made to Java programs to see which refactoring techniques were used most. They found that simple changes like renaming things and moving them around were very common. Some important changes, like inheritance and encapsulation, were not used as much. The study showed that certain types of changes were linked to fixing bad code. This helps developers know what changes might lead to other tasks when working on software.