I am writing a book. All documents are in one folder that has some sub-folders. What I need to do is: (a) Backup changes made (if any) in the master folder or subfolders as part of shutdown in a way that I can re-build the source document on another computer. (b) know what changes have been made in the sense of updated existing files or new files added in some sort of log file that, itself, is backed up.
The backup will be to an external disk.
Can you experts please recommend backup software? Free is nice of course but not at the expense of ease of use.