HistoryThe word spam is derived from Spam (uppercase), the name of the canned precooked meat product made by the Hormel Foods Corporation, which was used in a popular 1970 Monty Python sketch. Within the sketch, a restaurant's menu had the word Spam in nearly every selection and the script repeats the word "Spam" verbally which consequents an annoyance in one of the characters due to the repetition of the word. This annoyance is mimicked by the annoyance that electronic spam can cause within its victims.
The first occurrence of Internet spam occurred in 1978 when Carl Gartley sent an email to 393 people attempting to sell EDF to them. Gartley wrote one mass email to be sent on the ARPANET, rather than 393 individual emails, which was the standard email practice at the time.
The first major commercial spam incident occurred on March 5, 1984 when a pair of lawyers, Laurence Canter and Martha Siegel, sent out mass emails advertising their immigration law services. The couple was inevitably opposed for their sending of unwanted messages, but Canter and Siegel fought back by pleading their rights to free speech.
Due to the low cost and ease with which electronic messages can be sent, spam is one of the most ubiquitous problems in information and communication technologies. Spam is economically unique in that the receiver pays so much more than the sender does. The vast majority of spam is sent by networks of virus-infected computers, known as botnets, and therefore does not heavily cost the "sender." Statistical studies estimate that around 200 billion spam messages are sent per day and that 97% of all email messages are unwanted. Approximately 104 billion user hours per day go into reading and manually deleting spam . Spam is increasingly sophisticated, and the development of anti-spam software to combat it has created an arms race between spammers and computer-security software.
Cost benefits of spamming
From a perspective of cost-benefit analysis, spamming occurs because of the low cost of sending mass messages versus the high potential benefit of receiving sales, marketing, or other positive effects from those messages. One study of a botnet producing pharmaceutical spam, the most frequent type of spam , estimated that 3.5 million U.S. dollars of revenue could be generated per year, with the cost of distribution being relatively low and largely involving the labor and maintenance of botnet software . Anecdotally, the mass presence of spam alone suggests it is profitable, as if it were not profitable it would likely cease to exist.
Types of spam
Although spamming's most recognizable form is email spam, a wide range of other mediums are also susceptible to spam. For example, instant-messaging spam, common on systems such as Skype, is prevalent, with a report from Ferris research estimating 500 million spam IMs being sent in 2003 . Mobile-phone spam through text-messaging services exists, with American users reportedly receiving 1.5 billion spam messages in 2008. These messages often require the user to respond with "STOP" or "HELP" in order to prevent reception of further spam messages, thereby necessarily sapping unsolicited victims' time and attention. Social networks, such as Facebook and Twitter, are likewise not immune to spam. In social networking spam, spammers often use dummy accounts, which exist primarily to spam, or worse yet they hack legitimate users accounts in order to send links to friends and family members under the guise of a trusted contact. Online game messaging systems are vulnerable to spam, as users can flood channels with messages and thus disrupt legitimate communication. Blog spamming, or comment spam, exists on websites which allow commenting. Blog spammers fill comment sections with links to their blogs, thereby raising their page's rank in search engine results.
Spamming has many negative effects upon targets and is almost always recognized as wrong or bad. There are direct costs related to spam, such as unnecessary loss of human resources in combating it and environmental costs due to the energy resources which spam wastes, as well as collateral harms which often accompany them, such as financial theft, identity theft, data and intellectual property theft, virus and other malware infection, child pornography, fraud, and deceptive marketing.
Cows sharing the food resource of an open field could become a "tragedy of the commons" if some cows eat too much and deplete the resource for the entire herd
Email spam exemplifies a negative economic situation known as tragedy of the commons. A tragedy of the commons occurs through email spam because spammers are able to use up resources (e.g., bandwidth, energy, human labor) without bearing the costs of their consumption, as most of the cost of spamming lies on its recipients. This added cost consequently raises the price of goods and services associated with the commons (i.e., the internet, here); for example, spam can be associated with higher computer-security software costs and higher internet-service provider costs to end users.
Globally, spam energy use totals 33 billion kilowatt-hours (KWh) per year, with greenhouse gas emissions equivalent to 3.1 million passenger cars using 2 billion United States gallons of gasoline. Users' viewing and deleting of spam accounts for the largest spam-related energy drain--almost 18 billion kWh or almost 52% of total spam energy.
Search engine harm
Spamming can decrease the accuracy and relevancy of search results, thereby breaking the system for search-engine users. For example, the practice of blog spamming, in which spammers unsolicitedly place links to their website in the comments sections of blogs, can push a page to the top of Google search results due to the value of certain variables in its PageRank algorithm . This phenomenon can be combated by web developers who add rel="nofollow" attributes to HTML links in comment sections on sites they administer. This bit of HTML code tells search engine spiders to not follow that particular link, which denies potential spammers the opportunity to increase their search engine rankings through having that blog link to their spam site. 
Spam diverts its receivers' attention, thus wasting their time. The effort people must take to avoid spam in their email inboxes, blog comment sections, or other media can be tedious and annoying. While modern filtering software can help users avoid receiving many spam messages, the maintenance and installation of such filtering software itself can be seen as an unnecessary annoyance, and not every spam message can be filtered all the time. Manually filtering spam messages can be frustrating and time consuming. The time wasted by users viewing, deleting, and attempting to prevent spam is a negative effect imposed on them.
Categorizing something as spam is a very subjective, so oftentimes, items are labeled as spam when they should not be, and vice versa. This is a big problem with e-mails, as computer programs cannot always properly differentiate between items that belong in the spam folder, and those that do not. This can lead to people missing out on vital pieces of information because they look past it as useless due to the 'spam' label assigned.
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