You can rename an element, such as a class name, across all files in a project. This feature enables you to preview the possible changes in every location for that desired rename, and you can exclude individual occurrences from being renamed.
Instant rename lets you rename an element within a file. For instant rename, place the cursor on the name you want to rename, and press Ctrl+R; if instant rename is applicable to that variable, then all the instances of that variable are highlighted as follows:
A change in even one instance of that name will rename all other instances in the file simultaneously: