User`s guide

that can copy itself over and over again is relatively easy to produce.
Even such a simple virus is dangerous because it will quickly use all
available memory and bring the system to a halt. An even more
dangerous type of virus is one capable of transmitting itself across
networks and bypassing security systems.
Virus signature
The binary pattern of a virus, used by the antivirus program to detect
and eliminate the virus.
Worm
A program that propagates itself over a network, reproducing itself as
it goes. It cannot attach itself to other programs.
Glossary 184
Bitdefender Antivirus Plus 2015