What is the difference between viruses, worms, and Trojan horses?
A computer virus is a program written to alter the way a computer operates, without the permission or knowledge of the user. When executed a virus will often replicate itself by placing its own code into another program or replacing executable files with a copy of the virus-infected file. Worms are programs that duplicate themselves from system to system without the use of a host file. Where as a virus requires the spreading of an infected host file, worms usually exist inside other files, such as Microsoft Word or Excel documents, there is a difference between how worms and viruses use the host file. Usually a worm releases a document that already has the “worm” macro inside the document. The entire document will travel from computer to computer, so the entire document should be considered the worm. Trojan Horses are impostors. They claim to be something desirable but in fact are malicious.
