Spam is simply unwanted email or “junk mail” delivered to an email address often advertising various products or get-rich-quick schemes. (There is a lengthy article on spam at Wikipedia.)
If you are recieving a large quantity of spam messages, it is highly recommend that you continue and set up your email client to work with the Cal Poly Pomona spam service. In addition, there are other tips you can use that will help you reduce the amont of spam you receive in the first place.