Daily Copy Backup is a backup type in which only files and folders that have changed on that day are backed up but the archive attribute is not marked for each file and folder.

What is a Daily Copy Backup?
A backup type in which only files and folders that have changed on that day are backed up but the archive attribute is not marked for each file and folder. A daily copy backup is not a common type of backup operation.
It is typically used only if a user wants to take home copies of the files he or she has been working on during the day. Few administrators would be willing to schedule and run the system backup software just to make copies of these files, so users taking advantage of this backup type usually have a locally attached backup device along with a similar device attached to their systems at home.
Daily copy backups are likely to be performed on media such as Iomega Zip or Jaz disks rather than on tape.
Daily copy backups in Windows NT and Windows 2000
Daily copy backups are supported by the Microsoft Windows NT and Windows 2000 Backup utility.