Synchronize Files does what?

 I am a long time user of CTM stable release. I thought it would be neat to prevent files from being lost when I restore and have a old snapshot I don't like. Could I get the quick version of how to use sync files. Thanks for any help.  edit....   I just read CTM help. Probably should of done that first.  I see you can make a file into an older version.  But I want files that are only in the old snapshot.