The definition of spam - Unsolicited “junk” e-mail sent to large numbers of people to promote products or services. Sexually explicit unsolicited e-mail is called “porn spam”.

Also refers to inappropriate promotional or commercial postings to discussion groups or bulletin boards.

Some people define spam even more generally as any unsolicited e-mail. The act of sending spam is “spamming”. Someone who sends spam is a “spammer”.

The term “spam” comes from the Monty Python sketch where the name of the canned meat product is used so often that it crowds everything else out.

What can I do to prevent spam?

Never respond to unsolicited e-mail. To individuals who send spam, one response or “hit” among thousands of mailings is enough to justify the practice.

Never respond to the spams e-mail’s instructions to reply with the word “remove” unless you trust the company sending the e-mail. This is a ploy to get you to react to the e-mail and will alert the sender that your e-mail address is open and available to receive mail, which greatly increases it’s value. If you reply, your address may be placed on more lists, resulting in more spam.

Never click on a URL or web site address listed within a spam e-mail. This could alert the site to the validity of your e-mail address, potentially resulting in more spam.

Never sign up with sites that promise to remove your name from spam lists.
Although some of these sites may be legitimate, more often than not, they are address collectors. The legitimate sites are ignored (or exploited) by the spammers. In both cases, your address is recorded and valued more highly because you have just identified that your address is active.

An addresses that you can contact to report spam is

http://www.spammingbureau.com/email-abuse-and-spam-alerts.php
http://spam.abuse.net/

Great Information sites and programs, some free

http://reviews-zdnet.com.com/4520-3666_16-1013545.html
http://spam.abuse.net/userhelp/#report
http://www.spamfighter.com/
http://email.about.com/cs/spamfightingtips/index.htm?terms=spam
http://www.all-internet-security.com/
http://www.email-remover.com/contents/download.htm