Inevitably you may come across the need to compare two different versions of the same file.  Doing this with the naked eye is difficult and error prone.

A Diff Tool is designed to assist in this task.  I have used a few different Diff Tools, but I have found DiffMerge to be my recent favorite.  It allows you to select two different filesin Windows Explorer by selecting both files and then right-clicking.  In your menu there is an option to compare the two files.  You see the files side by side and you can copy from one side to the other.   Oh and... it's free.  But, don't take free for granted.  If you like it, donate to it so the project stays alive and available.