All computer viruses are manmade. A simple virus that can make a copy of 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. These programs periodically check your computer system for the best-known types of viruses.
Some people distinguish between general viruses and worms.
A worm is a special type of virus that can replicate itself and use memory, but cannot attach itself to other programs. The AVP Virus Encyclopedia contains over 2300 computer virus descriptions accessible by keyword search or alphabetical index. The AVP Virus Encyclopedia is also available as a freeware distribution. Antivirus online Online publication from IBM that covers news and information on viruses. Here, you'll find links to articles, tutorials, technical support, virus alerts, and hype alerts.