Computersight -

There are 4 types of major viruses found in most computer and shows how each virus harms your computer .

E-MAIL : 

E-mail Viruses usually travel around in e-mails and are spread out in a fast speed. E-mail virus are usually made by people and sent to random people by e-mail they dont know . After that virus has infected your computer, it starts sending the e-mail infected with virus to people who are in your contact list.

WORM:  

Worm is a small piece of software that finds a place to settle in your computer. After it settles it starts multiplying itself and creates more of its type in your Hard Disk. Worm does not delete your important data it just takes free space available in your hard disk.

TROJAN HORSE: 

Trojan Horse is one of the most dangerous virus i have ever faced. Trojan horse speeds up your processing and improves the speed of your computer but on the other hand torjan horse is deleting files from your computer and some files even required for the OS ( Operating system).

BOOT SECTOR VIRUS:

Boot sector virus is found in the files which are required for booting your computer. After boot sector virus has made its way to the files which are required to boot the computer it replaces the codes and you computer might not boot next time you turn it on it may also harm the CD rom or Floppy Disk area and they also might not boot next time you use them.

What Can you do ?

To protect you computer from such viruses i preffer you use the latest version of the antivirus from which ever company you like.

Do not Open E-mails from people you do not know

Do not download an attachment from an E-mail until you know what the attachment is.

Do not open E-mails which are found in junk folder.

Activate Firewall when downloading something from the internet.

Lock your floppy disk or USB with the switch on it so nothing can get into your computer from it.

Always Viruscan floppy disk And USB before opening them.

Do not go to sites you dont know about .