Data backup

The need for frequent data backup cannot be overstated.
Many data loss faults could be intentional or not, some examples are:

Turning off, rebooting, pulling the plug, current surge, etc., while in operation, will have unpredictable results.
The hard disk keeps information (including program code and the operating system) in the form of minuscule magnetic fields. With time, the magnetism fades out or is modified by the proximity of strong magnetic fields generated by telephone sets, speakers, magnetic business cards, and even the earth's magnetic field. Because of these factors, one day one bit might change, causing unpredictable results.

As one can see, the computer is usually accurate but it is not always accurate!

How to manage back-ups:

There are two types of backup:

- The frequent backup is the one that is done frequently (recommended daily) for the case when the computer crashes and the data becomes unrecoverable. This is the backup that is worth more than gold sometimes.
For this backup, avoid using the same media (diskette, tape, etc.) over and over again. Have ten and rotate them. Try to backup with a verify option for enhanced safety.

- The permanent backup is a backup copy that is done once in a while (recommended monthly) and sent off site, possibly to a locked safe.
This is necessary for the case of fire and burglary, in these cases, both the data within the computer and the backed up one might be lost at the same time.
Also, because the hard drive can be corrupted little by little with time, the permanent backup will have the original data before the corruption.
This usually happens with files that are not used for a long period of time, therefore its corruption is not detected.

See:

Data backup

File/Folder Encrypt/Decrypt

File/Folder Erase