What is a Computer Virus ?
Computer viruses are unwanted computer programs that can invade your hard drive and cause many different types of damage. Usually viruses are created when someone writes a computer program and embeds harmful software within that program. As soon as other people begin downloading that infected program onto their computers, the virus finds it's way in and negatively alters information stored in the computers. Not one computer virus is alike, there are millions of diverse programs that cause varying amounts of damage to a computer.
Just like human viruses, computer viruses spread rapidly as soon they are created and computers are exposed to the 'infection'. Although instead of traveling through the air, computer viruses disperse themselves all over the internet, sometimes you can get a virus just by clicking on a certain webpage. Many of times computer users will have a virus in their computer for a long period of time before it is detected or before it starts causing greater damage. Even when you have anti-virus software in your computer, it will not always find every virus because the anti-virus software can only find threats already known through that program's database.
You may ask, Why would someone create such counterproductive programs?
Well, there may not be an exact answer as to why humans knowingly create computer viruses other than to get some sort of revenge or to challenge their skills. No one will be able to prevent those people from creating viruses and exposing other computers to infection, the best thing for computer users to do to prevent such invasion is to use current anti-virus software and be cautious as to what sites they visit and what files they download.
When a virus finds it's way into your computer, it will hide in your hard drive and rapidly duplicate itself just like virus cells do in humans. You may not be able to tell, but every time you save your data, you are also saving the virus. Soon enough the virus has multiplied to such a great extent that it damages your data and causes major problems.
Although the computer's ROM (Read Only Memory) will not be affected by a virus, the RAM (Random Access Memory) and your computer's disks will surely be damaged. So if the virus is only in the RAM data in your computer, when you shut the computer down the virus will be lost as well as any other memory that had been held in the random access memory (RAM).
Unfortunately if the computer virus is on your hard drive or computer disk it will remain in the computer after you restart it and it will be there whenever you use the program again. If you switch from the infected program to another program without shutting down your computer, the virus will then attach to the other program. With that happening, that virus will slowly go through infecting all of your computer's programs before you have a clue that you computer is infected.
Currently, millions and millions of dollars are spent on efforts to protect computers from viruses and eliminate destructive virus programs.
Anti-virus programs offered by commercial and shareware sources were made solely to detect and fix programs that may be virus infected. These programs should be used to scan for viruses every time you put a disk into your computer and every time you start up your computer.