A virus is malicious computer code embedded within an executable program that victims activate on their machines, usually by opening an e-mail attachment.
Often viruses are sent with notes instructing recipients to open the attachment, such as the note with the Melissa Macro Virus that stated “here is the document you requested”, or with a tantalizing title such as “sexxxy.jpg”, or “naked wife”. Worms, on the other hand, require no action by the victims to become activated. They spread on their own from system to system without need for the victim to do anything. The Code Red Worm, for example, automatically sends itself to 99 Internet protocol (IP) addresses it generates. Once activated, viruses and worms can do anything from deleting files to sending themselves, together with documents on your hard drive, to some or all of the names in your address book or to any IP address. For the latest (in-depth) information about computer security in general and computer virus and virus protection in particular, visit the website at http://www.cert.org. To learn more about the history of the computer virus, please visit http://www.viruslist.com/eng/viruslistbooks.html?id=9 and http://www.virus-scan-software.com/virus-scan-help/answers/the-history-of-computer-viruses.shtml. The Virus Information Center (http://www3.ca.com/virusinfo) of Computer Associates International, Inc. also provides useful information (such as a virus encyclopedia) on computer viruses. The website at http://www.uta.fi/laitokset/virus/ provides more links to Internet resources on computer virus research and protection. For discussions about computer viruses in Chinese, check out the online BBS at http://bbs.logincom.com/bbs/cgi-bin/leoboard.cgi.
2. Melissa virusThe Melissa virus is a computer virus launched when a user opens an infected Microsoft Word 97 or Word 2000 document contained in either Office 97 or Office 2000. To learn more about the virus, check out the website at http://www.melissavirus.com.
3. Morris Worm 
Robert Tappan Morris is a Cornell University graduate student and the son of the former chief scientist for the US government's super-secret spy organization, the National Security Agency. In 1988 Morris wrote the first Internet worm, a software program that hopped from computer to computer in a network, jamming everything in its path. Morris admitted that he had written the program, and was fined and sentenced to community service. Since then he has finished graduate school in computer science at Harvard University, started a successful Internet company, and now is a faculty member at MIT (http://www.pdos.lcs.mit.edu/~rtm /).For more information about the worm including its source code, check out the website at http://www.worm.net. The website at http://www.snowplow.org/tom/worm/worm.html also provides a detailed look at the computer worm.
4．(US) Marine CorpsA branch of the US armed forces, composed chiefly of amphibious troops under the authority of the Secretary of the Navy. The United States Marines was established on November 10, 1775 after the US Congress authorized two battalions of Marines. For more information about the US Marine, check out its website at http://marines.com.
