It is e-mail that is unsolicited, unwanted, irrelevant, or inappropriate, especially commercial advertising in mass quantities. Spam is often sexually suggestive or offensive in other ways.
While the most widely recognized form of spam is e-mail spam, the term is applied to similar abuses in other media: instant messaging spam, spam in blogs, online classified ads spam, mobile phone messaging spam, social networking spam.
The best way to prevent spam is to protect your e-mail address. Don't respond to free offers or web sites that ask you for your e-mail. If you are already getting spam, then change your e-mail address. Your Internet service provider can also help prevent your receiving spam. You can generally fix your e-mail preferences to filter out much of the spam.
Things you can do to prevent spam
An article with steps to a spam-free inbox.
Easy steps to preventing spam
10 steps offer a very common sense approach to avoiding spam.