Spamming is the use of any electronic communications medium to send unsolicited messages in bulk. While its definition is usually limited to indiscriminate bulk mailing and not any targeted marketing, the term "spam" can refer to any commercially oriented, unsolicited bulk mailing perceived as being excessive and undesired. In the popular eye, the most common form of spam is that delivered in e-mail as a form of commercial advertising. However, over the short history of electronic media, people have done things comparable to spamming for many purposes other than the commercial, and in many media other than e-mail. Spammers have developed a variety of spamming techniques, which vary by media: e-mail spam, instant messaging spam, Usenet newsgroup spam, Web search engines spam, weblogs spam, and mobile phone messaging spam.
A common problem on sites like Wipipedia is that fake users are created which have no purpose other than to create articles or user pages with spam messages.
Spamming, the name of which derives from the Monty Python Spam sketch about SPAM brand processed meat, is economically viable because advertisers have effectively no operating costs beyond the management of their mailing lists. Because the barrier to entry is so low, the volume of unsolicited mail has produced other costs which are borne by the public (in terms of lost productivity and fraud) and by Internet service providers, which must add extra capacity to cope with the deluge. Spamming is widely reviled, and has been the subject of legislation in a number of jurisdictions, including the United States' CAN-SPAM Act of 2003.