|Search engine marketing|
Search engine optimization (SEO) is the process of affecting the visibility of a website or a web page in a search engine‘s “natural” or un-paid (“organic“) search results.[jargon] In general, the earlier (or higher ranked on the search results page), and more frequently a site appears in the search results list, the more visitors it will receive from the search engine’s users. SEO may target different kinds of search, including image search, local search, video search, academic search, news search and industry-specific vertical search engines.
As an Internet marketing strategy, SEO considers how search engines work, what people search for, the actual search terms or keywords typed into search engines and which search engines are preferred by their targeted audience. Optimizing a website may involve editing its content, HTML and associated coding to both increase its relevance to specific keywords and to remove barriers to the indexing activities of search engines. Promoting a site to increase the number of backlinks, or inbound links, is another SEO tactic.
The plural of the abbreviation SEO can refer to “search engine optimizers,” those who provide SEO service.
Webmasters and content providers began optimizing sites for search engines in the mid-1990s, as the first search engines were cataloging the early Web. Initially, all webmasters needed to do was to submit the address of a page, or URL, to the various engines which would send a “spider” to “crawl” that page, extract links to other pages from it, and return information found on the page to be indexed. The process involves a search engine spider downloading a page and storing it on the search engine’s own server, where a second program, known as an indexer, extracts various information about the page, such as the words it contains and where these are located, as well as any weight for specific words, and all links the page contains, which are then placed into a scheduler for crawling at a later date.
Site owners started to recognize the value of having their sites highly ranked and visible in search engine results, creating an opportunity for both 
Early versions of search 
By relying so much on factors such as keyword density which were exclusively within a webmaster’s control, early search engines suffered from abuse and ranking manipulation. To provide better results to their users, search engines had to adapt to ensure their results pages showed the most relevant search results, rather than unrelated pages stuffed with numerous keywords by unscrupulous webmasters. Since the success and popularity of a search engine is determined by its ability to produce the most relevant results to any given search, allowing those results to be false would turn users to find other search sources. Search engines responded by developing more complex ranking algorithms, taking into account additional factors that were more difficult for webmasters to manipulate. Graduate students at Stanford University, Larry Page and Sergey Brin, developed “Backrub,” a search engine that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm, PageRank, is a function of the quantity and strength of inbound links. PageRank estimates the likelihood that a given page will be reached by a web user who randomly surfs the web, and follows links from one page to another. In effect, this means that some links are stronger than others, as a higher PageRank page is more likely to be reached by the random surfer.
Page and Brin founded 
By 2004, search engines had incorporated a wide range of undisclosed factors in their ranking algorithms to reduce the impact of link manipulation. In June 2007, The New York Times’ Saul Hansell stated Google ranks sites using more than 200 different signals.
In 2005, Google began personalizing search results for each user. Depending on their history of previous searches, Google crafted results for logged in users.
In 2007, Google announced a campaign against paid links that transfer PageRank.
In December 2009, Google announced it would be using the web search history of all its users in order to populate search results.
Google Instant, real-time-search, was introduced in late 2010 in an attempt to make search results more timely and relevant. Historically site administrators have spent months or even years optimizing a website to increase search rankings. With the growth in popularity of social media sites and blogs the leading engines made changes to their algorithms to allow fresh content to rank quickly within the search results.
In February 2011, Google announced the “Panda update, which penalizes websites containing content duplicated from other websites and sources. Historically websites have copied content from one another and benefited in search engine rankings by engaging in this practice, however Google implemented a new system which punishes sites whose content is not unique.
In April 2012, Google launched the citation needed].
Relationship with search engines
By 1997, search engines recognized that webmasters were making efforts to rank well in their search engines, and that some webmasters were even manipulating their rankings in search results by stuffing pages with excessive or irrelevant keywords. Early search engines, such as Altavista and Infoseek, adjusted their algorithms in an effort to prevent webmasters from manipulating rankings.
In 2005, an annual conference, AIRWeb, Adversarial Information Retrieval on the Web was created to bring together practitioners and researchers concerned with search engine optimisation and related topics.
Companies that employ overly aggressive techniques can get their client websites banned from the search results. In 2005, the 
Some search engines have also reached out to the SEO industry, and are frequent sponsors and guests at SEO conferences, chats, and seminars. Major search engines provide information and guidelines to help with site optimization.Bing Toolbox provides a way from webmasters to submit a sitemap and web feeds, allowing users to determine the crawl rate, and how many pages have been indexed by their search engine.
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The leading search engines, such as 
Search engine crawlers may look at a number of different factors when crawling a site. Not every page is indexed by the search engines. Distance of pages from the root directory of a site may also be a factor in whether or not pages get crawled.
To avoid undesirable content in the search indexes, webmasters can instruct spiders not to crawl certain files or directories through the standard robots.txt file in the root directory of the domain. Additionally, a page can be explicitly excluded from a search engine’s database by using a meta tag specific to robots. When a search engine visits a site, the robots.txt located in the root directory is the first file crawled. The robots.txt file is then parsed, and will instruct the robot as to which pages are not to be crawled. As a search engine crawler may keep a cached copy of this file, it may on occasion crawl pages a webmaster does not wish crawled. Pages typically prevented from being crawled include login specific pages such as shopping carts and user-specific content such as search results from internal searches. In March 2007, Google warned webmasters that they should prevent indexing of internal search results because those pages are considered search spam.
A variety of methods can increase the prominence of a webpage within the search results. 301 redirects can help make sure links to different versions of the url all count towards the page’s link popularity score.
White hat versus black hat techniques
SEO techniques can be classified into two broad categories: techniques that search engines recommend as part of good design, and those techniques of which search engines do not approve. The search engines attempt to minimize the effect of the latter, among them 
An SEO technique is considered white hat if it conforms to the search engines’ guidelines and involves no deception. As the search engine guidelines although the two are not identical.
Search engines may penalize sites they discover using black hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines’ algorithms, or by a manual site review. One example was the February 2006 Google removal of both 
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Search engine optimization (SEO) copywriting is textual user‘s search list, while still producing readable and persuasive content.
Crawlers rely upon keyword placement within the text of an article, and typically disregard images.keyword density, the placement of the keywords, and the number of links to and from the page from other pages.
SEO copywriting is most often one of the various jobs of a copywriting agencies that offer SEO copywriting as part of comprehensive writing and editing services.
A freelance SEO copywriter will work with a client to determine the appropriate keywords needed to promote the client’s business. Online keyword research tools are then used to gather a list of potential phrases.
While an obvious goal of SEO copywriting is to cause the business’s or product’s web page to rank highly in a search, most experts in the field would argue that it is of secondary priority. The foremost goal of SEO copywriting is to produce succinct, effectively persuasive text for a well-written web page that will motivate the reader to take action. Writing that “optimizes” a search but offers little useful information or only weak persuasion is frowned upon in the profession as ineffective. At its worst, it becomes a costly resource inducing potential buyers to turn away from the site rather than generating sales. The main goal of the SEO copywriter remains writing interesting content that people want to read and link to.
SEO copywriters often work with “optimizers” who are more expert in the technical aspects of SEO. Together they will not only rewrite text but also alter the code to design a page that is most favored by search engines. It is not a clear, scientific process, however. Attempting to keep themselves competitive and defending against the composition strategies of so-called black hat SEOs, search engine designers today do not disclose the complex algorithmic processes of their search engines. In spite of the insights of optimizing technicians, SEO copywriting requires finesse and repeated experimentation to assess how the team’s page revisions will fare in a potential customer’s search.
As a marketing strategy
SEO is not an appropriate strategy for every website, and other Internet marketing strategies can be more effective, depending on the site operator’s goals.
SEO may generate an adequate 
Optimization techniques are highly tuned to the dominant search engines in the target market. The search engines’ market shares vary from market to market, as does competition. In 2003,  That market share is achieved in a number of countries.
As of 2009, there are only a few large markets where Google is not the leading search engine. In most cases, when Google is not leading in a given market, it is lagging behind a local player. The most notable markets where this is the case are China, Japan, South Korea, Russia and the Czech Republic where respectively Seznam are market leaders.
Successful search optimization for international markets may require professional translation of web pages, registration of a domain name with a top level domain in the target market, and web hosting that provides a local IP address. Otherwise, the fundamental elements of search optimization are essentially the same, regardless of language.
On October 17, 2002, 
In March 2006, 
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- Google Webmaster Guidelines
- Yahoo! Webmaster Guidelines
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- Google I/O 2010 – SEO site advice from the experts on YouTube – Technical tutorial on search engine optimization, given at Google I/O 2010.
This article uses material from the Wikipedia article Search Engine Optimization, which is released under the Creative Commons Attribution-Share-Alike License 3.0.