Spam is the common name given to unsolicited commercial emails, also known as junk mail. The name comes from a 1970's Monty Python skit where one of the characters goes to an upscale restaurant only to discover that every dish includes spam.

The first spam message was sent on May 3rd, 1978 when a marketing rep at a computer firm called DEC emailed an invitation to every West Coast user on the ARPANET, which was the precursor to the Internet we know today. Since then, spam has become the scorge of the net. It's estimated that up to 90% of all emails sent are spam messages. These messages hawk everything from stocks to prescription drugs. Some spam messages don't actually sell anything at all. Instead they try to trick the recipent into clicking on a link or downloading an attachment. Doing so infects the unsuspecting user's computer with malicious software and/or steals their personal information.

There are many varieties of anti-spam software and filters out there, including the CAPTCHA system, which blocks the automated programmers many spammers use by requiring a human to type in a code presented in an image. Unfortunately, spammers seem to keep finding ways to beat such systems and other filters as well. The battle to keep inboxes and blog comments spam free is never ending.