Antivirus are small software programs that should spread from one computer even to another and to interfere using computer operation.
A contamination might.. corrupt or delete data on your hard drive, use your e-mail program to spread itself to help other computers, or even erase everything within your hard disk.
Antivirus are often spread by way of attachments in e-mail information or instant messaging communications. That is why it is crucial that you never open e-mail attachments until you know who it’s from therefore you are expecting it.