A virus is a manmade program or piece of code that causes an unexpected, usually negative, event.
Viruses are often disguised games or images with clever marketing titles.

What is a Worm?

Computer Worms are viruses that reside in the active memory of a computer and duplicate themselves.
They may send copies of themselves to other computers, such as through email or Internet Relay Chat (IRC).

What is a Trojan Horse?

A Trojan horse program is a malicious program that pretends to be a benign application; a Trojan horse program purposefully does something
the user does not expect. Trojans are not viruses since they do not replicate, but Trojan horse programs can be just as destructive.
Many people use the term to refer only to non-replicating malicious programs, thus making a distinction between Trojans and viruses.

What is Spyware

Spyware is software that transmits information back to a third party without notifying the user. It is also called malware, trackware, hijackware,
scumware, snoopware or thiefware. Note: Some privacy advocates also call legitimate access control, filtering, Internet monitoring,
password recovery, security or surveillance software "spyware" because it could be used without notifying the users.

Facts About Spyware

* Spyware programs can be easily installed on your computer without your knowledge.
* Spyware can result in identity theft, data corruption, personal profiling and more.
* Your computer can get spyware when you download files, view an unsolicited email,
   visit Web pages that activate a 'drive-by download' or via other means.
* 90% of Internet-connected computers are infected with spyware.