Identifying the different types of viruses, and knowing how they spread from one computer to another, will help you keep your PC infection-free.

TYPES OF VIRUSES
File virus
A file virus infects program files. Once the affected program is running, it can infect other programs on your hard drive or on a floppy disk inserted in the A: drive.

Macro virus
A macro virus infects individual documents. It affects files created in programs that use macro programming language, such as Microsoft Office's Word and Excel programs. The most common macro virus is known as Concept. Once the Concept virus infects your computer, it clings to the "save" operation, passing on the infection to each and every document you save.

Boot and partition sector viruses
Boot and partition sector viruses infect the system software; that is, the special parts of the hard disk that enable your computer to start, or "boot" up. These viruses may prevent you getting your computer working at all. They work by removing your PC's start-up instructions and replacing them with their own set of instructions. You may need expert help if your computer catches this type of virus.

THE WAYS VIRUSES ARE SPREAD
Floppy disk
Always be wary of floppy disks as they are made to move files or programs between computers. The more machines that a disk is used on, the greater the chances of the disk picking up a virus and passing it on. Jaz and Zip disks can carry viruses in the same way as a floppy disk.

E-mail
Despite rumors to the contrary, you cannot catch a virus by simply opening and reading e-mail messages. However, be wary of opening a file attached to an e-mail as the file itself may carry a virus. As a general rule, do not open up files attached to unsolicited e-mail.

CD-ROM
You are safe with a CD-ROM (except in the extremely unlikely event that it was made with a virus). "ROM" stands for Read Only Memory, which means it will not accept viruses-or, indeed, any other kind of information. However, with recordable or rewritable CDs, you need to take the same precautions as with a floppy disk.

Internet
Don't download software of dubious origin from the Internet. Use a reputable company, such as Corel, Norton, Microsoft or McAfee.