Sometimes rather than making a backup of the entire site using the backup wizard, you'll run into a situation where you want to exclude certain folders. Usually these are folders that don't change often, or in some cases, folders with hundreds of images that don't need to be backed up. One of our users had just over 2GB of files in their images folder, and needed a way to not backup that folder; well here's how.
Upload a blank text file to the folder that you want to exclude and call it ".cpbackup-skip"
Now, when you run the backup wizard, it will backup all folders except folders with that file in it. When you want to include that folder again, just remove that file and you're back to normal!