Electronic spamming is the use of electronic messaging systems to send an unsolicited message (spam), especially advertising, as well as sending messages repeatedly on the same site. While the most widely recognized form of spam is email spam, the term is applied to similar abuses in other media: instant messaging spam, Usenet newsgroup spam, Web search engine spam, spam in blogs, , online classified ads spam, mobile phone messaging spam, Internet forum spam, junk fax transmissions, social spam, spam mobile apps, television advertising and file sharing spam. It is named after Spam, a luncheon meat, by way of a Monty Python sketch about a restaurant that has Spam in every dish and where patrons annoyingly chant "Spam!" over and over again.
Spamming remains economically viable because advertisers have no operating costs beyond the management of their mailing lists, servers, infrastructures, IP ranges, and domain names, and it is difficult to hold senders accountable for their mass mailings. Because the barrier to entry is so low, spammers are numerous, and the volume of unsolicited mail has become very high. In the year 2011, the estimated figure for spam messages is around seven trillion. The costs, such as lost productivity and fraud, are borne by the public and by Internet service providers, which have been forced to add extra capacity to cope with the deluge. Spamming has been the subject of legislation in many jurisdictions.
A person who creates electronic spam is called a spammer.
The term spam is derived from the 1970 Spam sketch of the BBC television comedy series Monty Python's Flying Circus. The sketch is set in a cafe where nearly every item on the menu includes Spam canned luncheon meat. As the waitress recites the Spam-filled menu, a chorus of Viking patrons drowns out all conversations with a song repeating "Spam, Spam, Spam, Spam… Spammity Spam! Wonderful Spam!", hence spamming the dialogue. The excessive amount of Spam mentioned references the preponderance of it and other imported canned meat products in the United Kingdom after World War II, as the country struggled to rebuild its agricultural base. Spam captured a large slice of the British market within the lower classes, and became a byword among British children of the 1960s for low-grade fodder due to its commonality, monotonous taste and low price, leading to the humour of the Python sketch.