What is a Computer Virus?
They are the reason most of us are still weary of sharing files and downloading programs. For more than a decade they have wreaked havoc on computers the world over, costing millions of dollars and lots of headaches in their wake. The culprit? Computer viruses. And despite the fact that the word "virus" has become commonplace, many of us are still unclear as to what exactly it means, and just how it can cause so much damage.
So just what is a computer virus?
Basically, a computer virus is a man-made program or code that can attach itself (usually without the user's consent) to either another program or a file. As this file travels to other computers, it spreads the infection. Interestingly, the only way a virus can become active is if it is triggered by a human action, such as executing a program or opening an infected file.
How are viruses spread?
Most commonly viruses are spread unknowingly from one infected computer to another via emails and instant messaging. Often, they are disguised as images, cards, and media files. They can also come from software or other programs downloaded from the Internet.
Certain viruses - called boot sector viruses - work to infect the system areas of floppy disks and hard drives. In this way, any computer that comes into contact with that disk is at risk for infection.
What do viruses do to computers?
A computer virus can be a minor annoyance, or a major problem. Its effects depend greatly on the intent of the person it was created by. Once on your computer, a virus might corrupt or worse, delete your data.
Some are designed to interfere with your system's operation, while others seek to copy themselves and spread to other computers. Both are dangerous, as they can corrupt and damage your files.
One thing a virus is not capable of doing is damaging any of your computer's physical hardware.
What's the difference between a virus, a worm and a Trojan horse?
Although all share some things in common, viruses, worms and Trojan Horses are all distinct (though equally bothersome) entities.
A worm functions similarly to a virus, as it spread from computer to computer. The difference is, it does require human assistance in order to do so. It can travel and copy itself much faster than a virus, making it more dangerous, and oftentimes, much more destructive.
A Trojan Horse, is also different from a virus. It is a program that pretends to be something other than what it is, such as a new game. Once you run the program, however, it can have a devastating effect. For example, it might send all your passwords to another person, or delete all the data on your hard drive.