Known as junk e-mail is any e-mail you did not ask for, but get it from people you do not know who want to sell something to you. A common synonym for spam is unsolicited bulk e-mail.
There are six different types of spam: Email spam: As noted earlier, email spam is something that we are very familiar with. It is a subset spam that involves nearly identical messages sent to numerous recipients by email.
Comment spam: Corporate blogs have quickly become an indispensable means of spreading the word on new products and services, as well as a means to obtain timely feedback from customers. As you might expect, spammers have been quick to subvert the ability to post comments for their nefarious purpose.
Instant messenger spam: Instant messaging (IM) spam run continue to take place periodically. The easiest way to stay on top of the situation would be to ignore any invites from unknown persons, and to consider links from strangers to be outright hostile, or a phishing attempt. Every IM service has some sort of profile page or directory listing from which spammers might harvest your contact details.
Junk fax: The fax machine is certainly not used as much as it was in its heyday, though many businesses still find themselves forced to rely on it occasionally. There are many ways to combat junk fax, assuming businesses are aware of them. For example, most fax machines these days come with the ability to store incoming fax transmissions in memory, giving users a chance to preview them prior to printing; more advanced models could even be configured to forward them as a PDF attachment to specified e-mail accounts.
Unsolicited Text Messages: SMS is one of those vectors that is hard to filter against. As a preventive measure, it’s always good not to give out one’s contact details by filling up “lucky draw” forms or surveys. On the positive front, the costs of sending text messages means spamming can become expensive quickly, and it is (comparatively) easy to trace the source of text messages and file a complaint with your provider.
Social networking spam: Spammers have started to flood social networking sites with spam and phishing attempts. Efforts for now are limited to messages or wall posts, though this will certainly evolve over time. For now, Twitter offers a great number of tools to protect its users, and it is possible to block or un-join accounts used to spam without notifying them about it. Where Facebook is concerned, my advice would be to impose a policy of only befriending those that you know explicitly. Ultimately, users need to be wary of clicking on URLs, given the widespread use of shortened URLs on most social networking media.
Damage caused by spam: 1- Communications overload 2- Waste of time 3- Irritation and discontent 4- The loss of an important email that accidentally gets deleted along with the plethora of spam 5- Criminalization of spam
Why do we care about spam?
Users want to.. look at quality pages on the web, interact without the trouble of moderation & surf safely.
Search engines want to.. provide good search results & profit from ads.