What is a trojan/worm/virus/logic bomb?
This FAQ answer was written by Theora: Trojan: Remember the Trojan Horse? Bad guys hid inside it until they could get into the city to do their evil deed. A trojan computer program is similar. It is a program which does an unauthorized function, hidden inside an authorized program. It does something other than what it claims to do, usually something malicious (although not necessarily!), and it is intended by the author to do whatever it does. If it’s not intentional, its called a ‘bug’ or, in some cases, a feature 🙂 Some virus scanning programs detect some trojans. Some virus scanning programs don’t detect any trojans. No virus scanners detect all trojans. Virus: A virus is an independent program which reproduces itself. It may attach to other programs, it may create copies of itself (as in companion viruses). It may damage or corrupt data, change data, or degrade the performance of your system by utilizing resources such as memory or disk space.