Spam means unsolicited irrelevant or inappropriate messages sent on the Internet to a large number of recipients.Almost everyone who has an email has received spam messages.People also spam forums thereby leaving links all over the site which might make google penalize your forum or blog.I am very sure you will not want to wake up one morning on your site and see 5000 automayed user registrations or comments made by a spam bot.

Please kindly share your experiences about spam and the best way to handle them so that others can learn