Search engine optimization (SEO), a subset of search engine marketing, is the process of improving the volume and quality of traffic to a web site from search engines via “natural” (“organic” or “algorithmic”) search results. SEO can also target specialized searches such as image search, local search, and industry-specific vertical search engines.
by understanding how search algorithms work and what human visitors might search for, to help match those visitors with sites offering what they are interested in finding. Some SEO efforts may involve optimizing a site’s coding, presentation, and structure, without making very noticeable changes to human visitors, such as incorporating a clear hierarchical structure to a site, and avoiding or fixing problems that might keep search engine indexing programs from fully spidering a site. Other, more noticeable efforts, involve including unique content on pages that can be easily indexed and extracted from those pages by search engines while also appealing to human visitors.
The term SEO can also refer to “search engine optimizers,” a term adopted by an industry of consultants who carry out optimization projects on behalf of clients, and by employees of site owners who may perform SEO services in-house. Search engine optimizers often offer SEO as a stand-alone service or as a part of a larger marketing campaign. Because effective SEO can require making changes to the source code of a site, it is often very helpful when incorporated into the initial development and design of a site, leading to the use of the term “Search Engine Friendly” to describe designs, menus, content managent systems and shopping cartsen that can be optimized easily and effectively.
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 a webmaster needed to do was submit 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, as well as any 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 “white hat” and “black hat” SEO practitioners. Indeed, by 1996, email spam could be found on Usenet touting SEO services. The earliest known use of the phrase “search engine optimization” was a spam message posted on Usenet on July 26, 1997.
Early versions of search algorithms relied on webmaster-provided information such as the keyword meta tag, or index files in engines like ALIWEB. Meta-tags provided a guide to each page’s content. But indexing pages based upon meta data was found to be less than reliable, because some webmasters abused meta tags by including irrelevant keywords to artificially increase page impressions for their website and to increase their ad revenue. Cost per thousand impressions was at the time the common means of monetizing content websites. Inaccurate, incomplete, and inconsistent meta data in meta tags caused pages to rank for irrelevant searches, and fail to rank for relevant searches. Web content providers also manipulated a number of attributes within the HTML source of a page in an attempt to rank well in search engines.
By relying so much upon factors 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. Search engines responded by developing more complex ranking algorithms, taking into account additional factors that were more difficult for webmasters to manipulate.
Sergei Brin, while graduate students at Stanford University, developed a search engine called “backrub” that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm is called PageRank, and is based upon the quantity and prominence of incoming 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.
Larry Page and Sergei Brin founded Google in 1998. On strong word of mouth from programmers, Google became a popular search engine. Off-page factors such as PageRank and hyperlink analysis were considered, as well as on-page factors, to enable Google to avoid the kind of manipulation seen in search engines focusing primarily upon on-page factors for their rankings. Although PageRank was more difficult to game, webmasters had already developed link building tools and schemes to influence the Inktomi search engine, and these methods proved similarly applicable to gaining PageRank. Many sites focused on exchanging, buying, and selling links, often on a massive scale. Some of these schemes, or link farms, involved the creation of thousands of sites for the sole purpose of link spamming.
To reduce the impact of link schemes, search engines have developed a wider range of undisclosed off-site factors they use in their algorithms. As a search engine may use hundreds of factors in ranking the listings on its SERPs, the factors themselves and the weight each carries can change continually, and algorithms can differ widely. The four leading search engines, Google, Yahoo, Microsoft and Ask.com, do not disclose the algorithms they use to rank pages. Some SEOs have carried out controlled experiments to gauge the effects of different approaches to search optimization, and share results through online forums and blogs. SEO practitioners may also study patents held by various search engines to gain insight into the algorithms.
By 1997 search engines recognized that some webmasters were making efforts to rank well in their search engines, and even manipulating the page rankings in search results. In some early search engines, such as Infoseek, ranking first was as easy as grabbing the source code of the top-ranked page, placing it on your website, and submitting a URL to instantly index and rank that page.
SEO techniques are classified by some into two broad categories: techniques that search engines recommend as part of good design, and those techniques that search engines do not approve of and attempt to minimize the effect of, referred to as spamdexing. Professional SEO consultants do not offer spamming and spamdexing techniques amongst the services that they provide to clients. Some industry commentators classify these methods, and the practitioners who utilize them, as either “white hat SEO”, or “black hat SEO”. Many SEO consultants reject the black and white hat dichotomy as a convenient but unfortunate and misleading over-simplification that makes the industry look bad as a whole.
An SEO tactic, technique or method is considered “White hat” if it conforms to the search engines’ guidelines and/or involves no deception. As the search engine guidelines, are not written as a series of rules or commandments, this is an important distinction to note. White Hat SEO is not just about following guidelines, but is about ensuring that the content a search engine indexes and subsequently ranks is the same content a user will see.
White Hat advice is generally summed up as creating content for users, not for search engines, and then make that content easily accessible to their spiders, rather than game the system. White hat SEO is in many ways similar to web development that promotes accessibility,although the two are not identical.
Black hat” SEO are methods to try to improve rankings that are disapproved of by the search engines and/or involve deception. This can range from text that is “hidden”, either as text colored similar to the background or in an invisible or left of visible div, or by redirecting users from a page that is built for search engines to one that is more human friendly. A method that sends a user to a page that was different from the page the search engined ranked is Black hat as a rule. One well known example is Cloaking, the practice of serving one version of a page to search engine spiders/bots and another version to human visitors.
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 review of a site.
One infamous example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices.Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google’s list.
