Backing up computer

I prefer Acronis for windows machines and Super duper for Mac ..these programs not only back up data they make a bootable duplicate of your hard drive .. plug it in and boot to it and everything is just where it was when backed up not just the files but the programs Too. If its the same or similar to the one in your computer just swap them and go on.
You really need two copies and the original to be secure ! .. the original on the computer and one in a back up drive on your desk (in case the computer crashes for quick access ) and one kept off property at your work or other famlly members or maybe Carbonite type service .. In case of theft, fire etc.
I also keep thumb drives for Documents, Photos or things I need to carry with me