In the early days, home computers were largely self-referential; people used them because they were interested in them. Now, computers are usually used for real-world tasks, yet they still need some navel-gazing attention at times!

User data is unique to the installation and cannot be replaced , and for that reason it is the central concern of system management.

Backup: To backup is to create a redundant copy, so that if anything should happen to the original file, you have recourse to the backup. The process can be as simple as copying files to diskettes, but this soon becomes a problem where files are too big for diskette, where there are too many files, or where too many diskettes are required.

A better solution is to use an archiver (such as WinZip) or a backup utility to create a single compressed file from a collection of data files, and to split this over as many diskettes as required. This uses fewer diskettes and allows large files to be backed up even if the file is larger than a diskette can hold.

For large data sets, you may need to use a bulk storage medium such as tape, Zip disk, CDR or similar. These are generally faster and more reliable than diskettes.

Malware management: There's more on safe computing and malware. Malware includes viruses, worms, trojans, and increasingly invasive commercial applications, and management has several parts:

Risk avoidance and evaluation - choice of applications and system setup
Risk avoidance and evaluation - user education and safe computing practice
Risk detection and destruction - choice and use of antivirus software
Keeping abreast of malware - antivirus updates and ongoing user education
Simply running an antivirus utility is not enough, even if it is kept up to date!