SEO (Search Engine Optimisation)

SEO (Search Engine Optimisation) is the study and business of improving search results. Includes a summary of search engine and SEO history, common SEO protocols, information on international search engines markets and types of SEO

Definition of SEO

SEO (Search Engine Optimisation or Search Engine Optimiser) refers to the study and business of improving search engine rankings in (unpaid) search engines. Depending on the end users’ georgraphic location and interest/industry, SEO tends to target different search engines and types of search, including multimedia search (image, video, audio), industry specific ‘vertical’ search, local search and social search. In most cases SEO is performed under the assumption that a better SERPs (Search Engine Result Pages) result will increase traffic to a website.
SEO is considered an online marketing strategy for increasing website traffic from search engine users. It works under the assumption that the higher a site ranks for a particular query in SERPs (Search Engine Results Pages), the higher the number of visitors from search engine users following links. Although there are many large networks related to SEO such as SMX, there is no official body that represents the SEO industry.
Furthermore, search engines generally don’t publish the rules of their search ‘algorithms’, which are used to determine the rank of a particular site or link. Extensive experimentation into SEO techniques and patents held by search engines has been documented and publicly released by prominent SEOs including Rand Fishkin, Barry Schwartz, Aaron Wall and Jill Whalen. However many SEO methods and metrics are widely disputed.
Despite this there are a few strategies that are commonly used in SEO. Typically SEO strategies consider how search engine ranking algorithms ‘work’ based off observation of different techniques in search engines and an understanding of the types of algorithms used by search engines. Also, SEOs (Search Engine Optimisers) work under the assumption that search engines use automated bots (also know as ‘spiders’ and ‘crawlers’) to index the contents of websites and related material like maps data and multimedia resources. Therefore SEOs will generally try to reduce the factors that might impede the ‘crawling’ of pages, for example most search engines cannot index content behind forms leading to the ‘deep web’.

Types of SEO

There are two schools of SEO that campaigns are typically classified into known as ‘white hat’ and ‘black hat’ SEO.

White hat SEO is a term associated with improving search ranking through increased ‘relevance’ via fixing site problems in information architecture, structure, coding and problems for search engine bot activity. This type of SEO is usually performed with the intention of creating long term results through improving site performance and relevance.

Black hat SEO may incorporate techniques used in ‘white hat’ SEO, however it usually has connotations of manipulative practices used to ‘trick’ search engines into ranking content highly. A common name for these practices is ‘spamdexing’ or the indexing of spam content. Examples of black hat SEO techniques include ‘keyword stuffing’ which is the repeated injection of useless or unrelated keywords into a web page and ‘link farming’ which is the ‘unnatural’ linking of websites together in order to build a large number of links to a page.

The main difference between ‘white hat’ and ‘black hat’ SEOs is that white hat SEO tend to follow the guidelines provided by search engines while black hat SEO does not. As a result, search engines may ban sites which employ black hat techniques.


According to industry analyst Danny Sullivan, the earliest known use of the phrase search engine optimization was a spam message posted on Usenet on July 26, 1997. However, it is generally accepted that webmasters having been optimizing search engines for websites since the early 1990s when the first internet search engines were created.

Early ‘SEO’ practices involved submission to a search engine via URL to the search engine in order to have a page crawled and indexed. Typically, search engines (still) collect this information into a cache on the search engine company’s servers, which is then processed using algorithms to determine the ‘weight’ and ‘relevance’ of the page to a particular set of words that would be used in search queries. Links from these pages are then scheduled for “re-crawling” at another date.

As search engines became more popular and important to online marketing in the mid 1990s, webmasters realized that the higher their search result the higher the traffic they were likely to receive. Many early search engines used meta data tags to rate a page’s relevance to a particular set of keywords, which made them open to manipulation as webmasters entered keywords in the meta tag and other site elements that were not truly relevant to the site’s actual keywords. In other cases, keywords were simply broken or incomplete. This over reliance on factors within the webmaster’s control lead to an increase in irrelevant pages and spam in search results. Search engines responded by creating new ranking algorithms which would be more difficult for webmasters to manipulate.

One of the most significant early developments was “Backrub”, which used a mathematical algorithm to rate the prominence / popularity of a website. Backrub was created by Larry Page and Sergey Brin (creators of Google) from Stanford University, and is used to calculate the popular PageRank metric, which estimates the likelihood of users visiting a page by randomly surfing the web based on the number of links to that page. This means that some links are stronger than others, as users are more likely to find some sites randomly based on the inbound links to that page.

The pair founded Google in 1998 which utilised the PageRank system. Google developed a large loyal following of users based on its simple design and because it could avoid the types of manipulation seen in other search engines using PageRank and other online / offline factors to rank pages. Despite this, webmasters were able to game the search engine using techniques similar to those used in the Inktomi search engine. “Link farming” techniques used include the mass buying and exchanging of links (often referred to as reciprocal or triangular depending on the context) and the creation of thousands of sites for the sole purpose of link building.

As search engines continue to develop, they are increasingly reliant on offline data which is difficult for webmasters and SEOs to manipulate. This includes regional / geographic data such as zipcodes (and even telephone verification) for local search. It also includes profile data like the age, sex, location and search history of users in an attempt to return more relevant results. Google now claims to rank sites based on more than 200 different factors.

Common SEO Protocols

There are several protocols that have become standard to major search engines.

robots.txt – this is a generic protocol to restrict the activity of search engine bots within websites. The file is placed at the root of the website and is read by search engines before they commence crawling. Instructions inside the file indicate to bots which files they can and can’t crawl.

sitemap.xml – many search engines including Google, Yahoo and MSN support the XML sitemaps protocol. This is an xml formatted list of files to be crawled which can be submitted to search engines. The protocol is designed to allow pages that are not linked from pages in a search engines index to be found by crawlers.

International Search Engine Share

The dominance of search engines in different geographic regions varies. For example, as of 2006 Google held around 40% of the US market but around 85-90% in Germany, and is generally considered the world’s dominant search engine. However, in Russia Yandex is the leading search engine, as is Baidu for China. Despite their dominance in different regions, it is generally accepted that these search engines use similar technologies in order to rank pages.

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