Mainly there are many varieties of
computer viruses, all of them can be categorized into two major types named
virus and
worms.
A
virus is actually a program, it replicates into files in your computer especially word documents, executable files (software installation files) or music files. Virus loves to attatch itself to another file.
Worm is also just a computer program created by naughty (and evil) programmer. Worm installs itself into a computer but does not attaching itself to any files. Worm is stand alone program, it does not infect other files.
Worm slows down your computer performance, duplicating itself so the same worm can install itself into another computer, worm attaches a copy of itself into moveable storage devices (such as usb pen drive, usb flash drive, multimedia memory card, usb external hard drive) or goes into another computer via local network.
Worm loves to spread itself into many computers, as many as it can while virus loves to copy itself and infect as many as possible.
