Glossary:

Virus:
A computer virus is a software executable code segment which is covertly incorporated into the executable program code files (i.e. EXE, BIN, BAT, SYS, COM, DLL, etc.) or data files of a computer or computer network and is activated when the host programs executes. It can cause system crashes, changes in data or complete erasure of hard drives.

Spy ware:
Spyware , Trojans , Adware are unwanted software that is installed while surfing the Internet, and that typically uses the Internet in the process of exploiting the user and the user's machine.

Spam:
Spam is unsolicited e-mail on the Internet. From the sender's point-of-view, it's a form of bulk mail, often to a list culled from subscribers to a Usenet discussion group or obtained by companies that specialize in creating e-mail distribution lists. To the receiver, it usually seems like junk e-mail. In general, it's not considered good netiquette to send Spam. It's generally equivalent to unsolicited phone marketing calls except that the user pays for part of the message since everyone shares the cost of maintaining the Internet.

Cookies:
A cookie is a message given to a Web browser by a Web server. The browser stores the message in a text file. The message is then sent back to the server each time the browser requests a page from the server. The main purpose of cookies is to identify users and possibly prepare customized Web pages for them.