On the Internet, the term "spam" has nothing to do with the familiar canned meat product. Rather, spam is a term for junk email. No one knows for sure how the term came into common use when talking about email -- some suspect a connection to the Monty Python Spam song -- but just like junk in your home mailbox, spam gets in the way of the mail you want to read and can occasionally pose a security risk.
Identifying and Avoiding Spam
Every email client and Web mail service provides spam filtering. An automated system looks through messages to weed out the junk, depositing it in a separate folder and ideally leaving only useful messages in your inbox. In practice, some spam dodges the filter.
Although annoying, most spam consists of harmless advertisements and newsletters. Usually, the best solution is to delete the junk and move on. Your mail service might also offer a "Mark as Junk" option to get rid of a message while helping to improve the filter. Sometimes, due to the content of an email, a legitimate message might be marked as spam. Check through the subject lines in your spam folder every few days to make sure the filter didn't catch any real mail. If it did, press the "Not Spam" or "Not Junk" button to move the email to your inbox.
Viruses and Phishing
Not all junk messages are benign advertisements; some spam emails contain viruses that can infect your computer. As a safety precaution, don't open email attachments you aren't expecting, especially if they come from unfamiliar sources. Another type of threat, phishing attacks, attempt to trick you into giving up personal information. The best defense against phishing is to avoid clicking links in your email. If an email claims to come from your bank and asks for information, for example, contact your bank directly rather than click a link or reply to the message. Even the "Unsubscribe" link from an unfamiliar source is dangerous -- it might notify a spammer that your email address works, opening the door to more junk.