A virus is a program that can make copies of itself and spread itself from one machine to another without the help of the user. Viruses carry out other actions.varying from the annoying (altering a computer's homepage) to the damaging (deleting files). Viruses are computer programs and therefore can delete files, format hard drives, and overwrite the BIOS. However, some viruses do nothing at all.
How do viruses spread?
Email-borne virus: An executable file is attached to an email, which usually has a tempting or intriguing subject line to encourage the receiver to open the email. When the attachment is opened, the virus is activated, and the user's computer becomes infected. Just like a human virus it will then usually infect others (in this case, by attaching itself to new email messages that it sends to your contacts) while going about it's other task of attacking the carrier. So once your computer is infected, all your friends and contacts are at risk as well.
Email virus: Unlike an attached file that the user must execute, email viruses are embedded within the email.. Attachments may be involved and will automically execute when the user reads the email. Thus, email viruses differ from email-borne viruses, the latter which require users actually open the attachment in order to become infected. Historically, email viruses have targeted Microsoft Outlook and Outlook Express users, though theoretically other mail clients could pose a risk. In any event, if an attachment is involved the user can still choose to open it and become infected, as was the case with the BadTrans.B worm. For this reason, it is equally important to understand both how to prevent attachments from being automatically executed by the mail client and how to recognize potentially harmful attachment types. Any executable type attachment has the potential to be infected.
Infected files: Be careful when downloading files from the internet. If a file that you download is infected and your computer is not protected then it is infected immediately. The same applies to software distributed on disks, check them before installing anything - whatever the source.
Stealth download: A misleading dialogue box can often cause the user to unwittingly accept a download/installation without realising it.
Symptoms
A virus can basically cause practically every kind of computer problem possible, including slower operation, decreased memory, erratic disk drive activity, loss of functionality, crashes and lock-ups, sometimes displaying messages, or even playing musical tunes, however many give no initial sign of their presence. So don't assume that your not infected if nothing seems to be wrong, likewise don't instantly assume that you have a virus when your computer misbehaves.
Options
If you do not need or recognise a file or attachment, don't open it.
It's really vital to have anti-virus software on your computer with email use and abuse increasing everyday. Many people have alarms fitted to their cars and property these days. Fit one to your email - it's just as important. Your computer contains your personal property just as your home does. [Click here]
