what do virus do ? Posted by MOHAMMED ABDUL HAMEED on 1:29 PM

I'm going to present an easy to understand but detailed explanation of viruses and other types of malicious software. For now, it's enough to understand that viruses are potentially destructive software that spreads from program to program or from disk to disk. Computer viruses, like biological viruses, need a host to infect; in the case of computer viruses this host is an innocent program. If such a program is transferred to your PC, other programs on your PC will become infected. (I'll shortly explain in more detail how this happens.) Even though some viruses do not intentionally damage your data, I consider all viruses to be malicious software since they modify your programs without your permission with occasional disastrous results.
The bottom line is that if you have a virus, you are no longer in control of your PC. Every time you boot your PC or execute a program the virus may also be executing and spreading its infection. While most viruses haven't been written to be destructive, almost all viruses can cause damage to your files--mostly because the viruses themselves are very poorly written programs. If viruses destroy nothing else, they destroy your trust in your PC--something that is quite valuable