Spam

In short: Spam is unwanted mass messages, mostly advertising or fraud.

In more detail: The term comes from a sketch by the group Monty Python. Spam exists by e-mail, SMS, messenger, comment fields and forums.

In Depth

Advertising by e-mail without consent is an unreasonable nuisance in Germany (§ 7 UWG). Double opt-in is common.

Spam filters use word lists, reputation lists, behaviour analysis and machine learning. See spam e-mail.

Do not publish your address, use disposable addresses, never reply to spam.

See also: Spam E-mail, Phishing, Spear Phishing