SEO has been about as long as search engines have existed and is one of the earliest forms of internet marketing, the first search engines counted on directories for their search databases. They were limited in the detail of results and mainly worked through categorisation. Web crawlers were intrinsic in a development of the web by spidering the internet with bots that gathered information on websites. Early search relied exclusively on keyword density in the document to evaluate its relevance to the search query.
And so the story SEO began, the first flourish of success came through keyword stuffing, injecting hidden text into the page to maximise its keyword density. The text was often hidden by tiny font size or matching font colour with the background, by increasing the keyword density early search engines such as Magellan, Excite, Infoseek, Inktomi, Northern Light, AltaVista, and Yahoo were fooled into returning keyword stuffed sites to the top. Limits on keyword density ratio were introduced in early spam algorithms and those limits still exist today.
Google rose to prominence in early 2000 with a new system called PageRank. Instead of looking at keyword density of a document PageRank would look instead at how many inbound links a document had and determine its score by the weight of inbound links and relevancy by anchor text. Google had PageRank on Google toolbar that ranked websites out of 10. The more important the website the higher the PageRank.
Pagerank was named after one of Google’s founders Larry Page and is the algorithm used to assign a score to each page on the web based on link quality and link quantity. PageRank was developed at Stanford University by Larry Page and Sergey Brin in 1996 in a research paper called “Bringing Order to the Web”. Pagerank occurs through when sites link to each other on the world wide web and the more authoritative the site the greater weight of the links. PageRank was patented (U.S. Patent 6,285,999) to Stanford University and licensed to Google in exchange for shares, the Pagerank patent runs out in 2017.
Google and the innovative Pagerank were a phenomenal success, as well as returning more relevant results surpassing its competitors Google automatically penalised keyword stuffing and hidden text. And so inbound links became the main priority for the SEO Industry.
Google used to give great value to directories such as DMOZ and Yahoo and early optimisers inflated their inbound links by subscribing to as many directories as they could. Link farms emerged with adverts selling inclusion to artificially boost site authority. Link Exchange where webmasters exchanged links to other sites were founded. So Google altered their ranking system to deprecate reciprocating links and link directories. Early SEO stories included optimisers that gamed the system by gaining the most non-reciprocating links.
But it was links from high PageRank sites that most determined search positions, realising the potential to alter search the inevitable happened, money started changing hands for links. The link seller was born. The next innovation in SEO came through automation, link selling became automated, content became automated and comment spam got automated too, it was an epidemic. Google again responded to the challenge, the nofollow tag was invented that would discount an outbound link and content and link algorithms were released as a solution.
Difference between Bing and Google
Bing is Google main rival for English search. Owned by Microsoft, Bing also evaluates inbound links but is thought to look at semantic structure and keyword in URL as other signals to rank websites. Google is moving more towards artificial intelligence to determine results introducing RankBrain and user metrics.