2.  a crime committed on a computer network, esp. the Internet

3.  a microcomputer user who attempts to gain unauthorized access to proprietary computer systems

4.  refers to someone who uses emails as an offensive force. They would usually send a company a very threatening email stating that they will release some confidential information, exploit a security leak, or launch an attack that will harm a company's network. They will request a paid sum of money to prevent the threat from being carried out, a bit like black-mailing.

5.  someone who uses a computer network or the internet to destroy computers for political reasons. It's just like a regular terrorist attack because it requires highly skilled individuals, millions of dollars to implement, and years of planning.

6.  malicious code that replicates itself. New viruses are discovered daily. Some exist simply to replicate themselves. Others can do serious damage such as erasing files or even rendering the computer itself inoperable.

7.  similar to a virus. They replicate themselves like viruses, but do not alter files like viruses do. The main difference is that worms reside in memory and usually remain unnoticed until the rate of replication reduces system resources to the point that it becomes noticeable.

8.  is called such as a reference to the story of the Trojan horse from Greek legend. It is a malicious program disguised as a normal application. Trojan horse programs do not replicate themselves like a virus, but they can be propagated as attachments to a virus.

9.  a type of application you install to protect your system from viruses, worms and other malicious code. Most antivirus programs will monitor traffic while you surf the Web, scan incoming email and file attachments and periodically check all local files for the existence of any known malicious code.

10.  A unique string of bits, or the binary pattern, of a virus. The virus signature is like a fingerprint in that it can be used to detect and identify specific viruses. Anti- virus software uses the virus signature to scan for the presence of malicious code.

11.  To move an infected file, such as a virus, into an area where it cannot cause more harm. Antivirus software come with quarantine options so that the user also can keep track of virus activity.

12.  MARK THIS ONE OFF

13.  an undocumented way to get access to a computer system or the data it contains; type of malware

14.  the act of forging the header information on an email so that it appears to have originated from somewhere other than its true source.

15.  a protective barrier between your computer, or internal network, and the outside world; a security feature for your computer

16.  any program offered free of charge

17.  term that refers to various types of software that can cause problems or damage your computer.  can consist of viruses, worms, Trojan horses, macro viruses, and backdoors.

18.  any flaw or weakness in the network defense that could be exploited to gain unauthorized access to, damage or otherwise affect the network.

19.  Gaining access to a network or a computer without proper approval.

20.  A name used to gain access to a computer system.

21.  A secret series of characters that enables a user to access a file, computer, or program.