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SEO began in the mid- 1990s , as the first search engines were cataloging the early Web . Initially, all a webmaster needed to do was submit a site to the various engines which would run spiders , programs to "crawl" the site, and store the collected data. The search engines then sorted the information by topic, and served results based on pages they had spidered. As the number of documents online kept growing, and more webmasters realized the value of organic search listings, so popular search engines began to sort their listings so they could display the most relevant pages first. This was the start of a search engine versus webmaster game that continues to this day.
At first search engines were guided by the webmasters themselves. Early versions of search algorithms relied on webmaster-provided information such as category and keyword meta tags . Meta tags provided a guide to each page's content. When some webmasters began to abuse meta tags, causing their pages to rank for irrelevant searches, search engines abandoned their consideration of Meta tags and instead developed more complex ranking algorithms , taking into account factors that were more diverse, including:
Text within the title tagDomain nameURL directories and file namesHTML tags : headings, bold and emphasized textKeyword densityKeyword proximityAlt attributes for imagesText within NOFRAMES tagsBy relying so extensively on factors that were still within the webmasters' exclusive control, search engines continued to suffer from abuse and ranking manipulation. In order to provide better results to their users, search engines had to adapt to ensure their SERPs showed the most relevant search results, rather than useless pages stuffed with keywords by unscrupulous webmasters. This led to the rise of a new kind of search engine.
Google was started by two PhD students at Stanford University , Sergey Brin and Larry Page , and brought a new concept to evaluating web pages. This concept, called Page Rank , has been from the start important to the Google algorithm [1] . Page Rank relies heavily on incoming links and uses the logic that each link to a page is a vote for that page's value. The more incoming links a page had the more "worthy" it is. The value of each incoming link itself varies directly based on the Page Rank of the page it comes from and inversely on the number of outgoing links on that page.
With help from Page Rank, Google proved to be very good at serving relevant results. Google became the most popular and successful search engine. Because Page Rank measured an off-site factor, Google felt it would be more difficult to manipulate than on-page factors.
But manipulated it was. Webmasters had already developed link manipulation tools and schemes to influence the Inktomi search engine. These methods proved to be equally applicable to Google's algorithm. Many sites focused on exchanging, buying, and selling links on a massive scale. Page Rank's reliance on the link as a vote of confidence in a page's value was undermined as many webmasters sought to garner links purely to influence Google into sending them more traffic, irrespective of whether the link was useful to human site visitors.
It was time for Google-and other search engines-to look at a wider range of off-site factors. There were other reasons to develop more intelligent algorithms. The Internet was reaching a vast population of non-technical users who were often unable to use advanced querying techniques to reach the information they were seeking and the sheer volume and complexity of the indexed data was vastly different from that of the early days. Search engines had to develop predictive, semantic , linguistic and heuristic algorithms.
A proxy for the Page Rank metric is still displayed in the Google Toolbar , but Page Rank is only one of more than 100 factors that Google considers in ranking pages.
Today, most search engines keep their methods and ranking algorithms secret. A search engine may use hundreds of factors in ranking the listings on its SERPs; the factors themselves and the weight each carries may change continually.
Much current SEO thinking on what works and what doesn't is largely speculation and informed guesses. Some SEO's have carried out controlled experiments to gauge the effects of different approaches to search optimization.
The following, though, are some of the considerations search engines could be building into their algorithms, and the list of Google patents [2] may give some indication as to what is in the pipeline:
Age of siteLength of time domain has been registeredAge of contentRegularity with which new content is addedAge of link and reputation of linking siteStandard on-site factorsNegative scoring for on-site factors (for example, a dampening for sites with extensive keyword meta tags indicative of having being SEO-ed)Uniqueness of contentRelated terms used in content (the terms the search engine associates as being related to the main content of the page)Google Page Rank (Only used in Google's algorithm)External links, the anchor text in those external links and in the sites/pages containing those linksCitations and research sources (indicating the content is of research quality)Stem-related terms in the search engine's database (finance/financing)Incoming back links and anchor text of incoming back linksNegative scoring for some incoming back links (perhaps those coming from low value pages, reciprocated back links, etc.)Rate of acquisition of back links: too many too fast could indicate "unnatural" link buying activityText surrounding outward links and incoming back links A link following the words "Sponsored Links" could be ignoredUse of "rel=nofollow" to suggest that the search engine should ignore the linkDepth of document in siteMetrics collected from other sources, such as monitoring how frequently users hit the back button when SERPs send them to a particular pageMetrics collected from sources like the Google Toolbar , Google Ad Words / Ad sense programs, etc.Metrics collected in data-sharing arrangements with third parties (like providers of statistical programs used to monitor site traffic)Rate of removal of incoming links to the siteUse of sub-domains, use of keywords in sub-domains and volume of content on sub-domains. and negative scoring for such activitySemantic connections of hosted documentsRate of document addition or changeIP of hosting service and the number/quality of other sites hosted on that IPOther affiliations of linking site with the linked site (do they share an IP? have a common postal address on the "contact us" page?)Technical matters like use of 301 to redirect moved pages, showing a 404 server header rather than a 200 server header for pages that don't exist, proper use of robots.txtHosting uptimeWhether the site serves different content to different categories of users ( cloaking )Broken outgoing links not rectified promptlyUnsafe or illegal contentQuality of HTML coding, presence of coding errorsActual click through rates observed by the search engines for listings displayed on their SERPsHand ranking by humans of the most frequently accessed SERPsSearch engine operators became interested in the SEO community in the late 1990s. A number of high profile SEO community leaders established contractual relationships with search engines for advertising and consulting purposes. These early contacts led to an amelioration of some hostile feelings between the search optimization and search engineering communities.
In early 2000 , search engines and SEO firms attempted to establish an unofficial " truce ." There are several tiers of SEO firms, and the more reputable companies employ content-based optimizations which meet with the search engines' (reluctant) approval. These techniques include improvements to site navigation and copy writing, designed to make web sites more intelligible to search engine algorithms.
Some search engines have also reached out to the SEO industry, and are frequent sponsors and guests at SEO conferences and seminars. In fact, with the advent of paid inclusion , some search engines now have a vested interest in the health of the optimization community.
New sites do not need to be "submitted" to search engines to be listed. A simple link from an established site will get the search engines to visit the new site and spider its contents. It is rarely more than a few days from the acquisition of the link to all the main search engine spiders visiting and indexing the new site.
Once
the search engine has found the new site, it will generally visit and
index all the pages on the site, as long as all the pages are linked to
with standard <a href> hyperlinks. Pages which are accessible
only through Flash or Java script links may not be findable by the
spiders.
Webmasters can instruct spiders to not index certain files or directories through the standard robots.txt file in the root directory of the domain. Standard practice requires a search engine to check this file upon visiting the domain. The web developer can use this feature to prevent pages such as shopping carts or other dynamic, user-specific content from appearing in search engine results.
For those search engines who have their own paid submission (like Yahoo), it may save some time to pay a nominal fee for submission.
So-called "white hat" methods of SEO involve following the search engines' guidelines as to what is and what isn't acceptable. Their advice generally is to create content for the user, not the search engines; to make that content easily accessible to their spiders; and to not try to game their system. Often webmasters make critical mistakes when designing or setting up their web sites, inadvertently "poisoning" them so that they will not rank well. White hat SEO attempts to discover and correct mistakes, such as machine-unreadable menus, broken links, temporary redirects, or a generally poor navigation structure that places pages too many clicks from the home page.
Because search engines are text-centric, many of the same methods that are useful for web accessibility are also advantageous for SEO. Methods are available for optimizing graphical content, including ALT attributes, and adding a text caption. Even Flash animations can be optimized by using an OBJECT element that contains equivalent HTML content [3] .
Some methods considered proper by the search engines:
Using a short and relevant title to name each page.Editing web pages to replace vague wording with specific terminology that is relevant to the subject of the page.Increasing the amount of original content on a site.Using a reasonably-sized, accurate description meta tag without excessive use of keywords, exclamation marks or off topic terms.Ensuring that all pages are accessible via regular links, and not only via Java, Java script or Macromedia Flash applications; this can be done through the use of a page listing all the contents of the site (a Site map)Developing links via natural methods: Google doesn't elaborate on this somewhat vague guideline. Dropping an email to a fellow webmaster telling him about a great article you've just posted, and requesting a link, is most likely acceptable.Participating in a web ring with other web sites as long as the other web sites are independent, share the same topic, and are of comparable quality.Main article: Spamdexing
Spamdexing is the promotion of irrelevant, chiefly commercial, pages through deceptive techniques and the abuse of the search algorithms. Many search engine administrators consider any form of search engine optimization used to improve a website's page rank as spamdexing. However, over time a widespread consensus has developed in the industry as to what are and are not acceptable means of boosting one's search engine placement and resultant traffic.
As search engines operate in a highly automated way it is often possible for webmasters to use methods and tactics not approved by search engines to gain better ranking. These methods often go unnoticed unless an employee from the search engine manually visits the site and notices the activity, or a change in ranking algorithm causes the site to lose the advantage thus gained. Sometimes a company will employ an SEO consultant to evaluate competitor's sites, and report "unethical" optimization methods to the search engines.
Spamdexing often gets confused with legitimate search engine optimization techniques, which do not involve deceit. Spamming involves getting web sites more exposure than they deserve for their keywords, leading to unsatisfactory search results. Optimization involves getting web sites the rank they deserve on the most targeted keywords, leading to satisfactory search experiences.
When discovered, search engines may take action against those found to be using unethical SEO methods. In February 2006, Google removed both BMW Germany and Ricoh Germany for use of these practices. [4]
In 2002, search engine manipulator SearchKing filed suit in an Oklahoma court against the search engine Google . SearchKing's claim was that Google's tactics to prevent spamdexing constituted an unfair business practice. This may be compared to lawsuits which email spammers have filed against spam-fighters, as in various cases against MAPS and other DNSBL's . In January of 2003, the court pronounced a summary judgment in Google's favor. [5]
A webmaster who wants to maximize the value of a web site can read the guidelines published by the search engines, as well as the coding guidelines published by the World Wide Web Consortium . If the guidelines are followed, and the site presents frequently updated, useful, original content, and a few meaningful, useful inbound links are established, it is usually possible to obtain a significant amount of organic search traffic.
When a site has useful content, other webmasters will naturally place links to the site, increasing its Page Rank and flow of visitors. When visitors discover a useful web site, they tend to refer other visitors by emailing or instant messaging links.
As a result, SEO practices that improve web site quality are likely to outlive short term practices that simply seek to manipulate search rankings. The top SEO's recommend targeting the same thing that search engines seek to promote: relevant, useful content for their users.
This article content source from wikipedia
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