What is a computer virus?

A computer virus is a small software program that attaches itself to a program or file. It is designed to spread from one computer to another and interfere with computer operation. To avoid viruses, it's essential that you have internet security software.

What can a computer virus do to my computer?

A computer virus can corrupt or delete data on your computer, use your e-mail program to spread itself to other computers, or even erase everything on your hard disk.

Sometimes you may notice a computer virus has infected your system. It may slow down your system, cause your computer to behave erratically or delete files.

Other times, a computer virus will do nothing to call attention to itself and remain hidden on your computer until you run the infected program. Often it is only when users run a virus scan that they realise their computer is infected with a virus.

While some viruses can be destructive, others may only reproduce themselves but do nothing else.

How is a computer virus different from a worm virus or trojan virus?

A computer virus is often confused with a worm virus or trojan horse virus. All three types of virus can harm a computer’s data or performance.

A worm virus is designed, like a computer virus, to adversely impact your computer files. However, it is the way it travels that makes it different from a computer virus. Instead, a worm spreads through computer networks of its own volition.

A trojan horse virus is again different to a virus. A trojan horse virus is a software program that appears to be harmless but hides malicious functions.

How does a computer virus move?

Viruses are most easily spread through attachments to e-mail messages or instant messaging messages. That is why it is essential that you never open an e-mail attachment unless you know who it is from and you are expecting it.

You can also get a computer virus when you download a file or program from the internet. A computer virus can be hidden in software or other files or programs you download.