Computer worm
Worm is a program which destroys computers by repeating proliferation. Although ones that stays latent in CD-ROM or floppy disks and infects used to be popular before, ones that proliferates explosively through the Internet like e-mail appeared with the spread of the Internet now. It is sometimes regarded as a kind of computer virus, "worm type virus", but it is different from them in that it is activated without living on other programs or it is developed with easy technologies like script languages or macro. Because it is easy to develop, its subspecies also easily appeared. The popular worms are "LOVE LETTER" or "Happy99".