What is refactoring?

"Refactoring is a disciplined technique for restructuring an existing body of code,
altering its internal structure without changing its external behavior."
So when refractory, the functionality of the application does not change, but the internal structure improves, which makes room for adding new functionality or makes it easier to fix issues at a later stage. Complexity Map indicates which areas of the application contain too much accidental complexity and thus are a candidate for refractory.