One misconception that users harbor and which we would like to clear right away is that there are some viruses which can infect a write-protected disk. This is not possible. A write-protect tab is an (almost) fool proof defence against viruses - present or future. We say `almost` as there are two possibilities of a write-protected disk getting infected:
- if the drive has become faulty
- when the tab used is semi-transparent or transparent. With such a tab, the infra-red light passes through the notch, leading the drive to believe that the tab is not present.
The latter, of course, does not refer to the 3.5-inch floppy disks which have a built-in, sliding, plastic write-protect tab.

Trojan Horses or simply Trojans, are one of the simplest form of destructive programs. They derive their name from the ancient Greek fable, `Helen Of Troy`, where a wooden horse was gifted to the enemy and was taken inside their fort. The `gift`, actually contained soldiers, and once inside, they emerged to overcome the feeble resistance and created havoc. Whoever said one must not look a gift horse in the mouth?!

On the lines of the wooden horse, a Trojan is a program which is supposed to do something useful, but, executed, at a given time or event, it triggers off and does something totally different, usually harmful.