A Short History of Search Engine Optimization

1. The Early Years
The actual term (SEO) started being thrown around in 1997. Content provider and Webmasters began doing SEO in the mid
1990's. What is SEO today however is though quite a drastic revolution from what constituted SEO back then.
People started to experiment with SEO concepts in the time when Yahoo was the dominant player in the search engine space. Back then webmasters needed only to submit their URLS's the different search engines. These search engines would send spiders to crawl and index the sites. As soon as the realization was made of having your site on the front page of a search engine's results, they began in earnest looking for ways how to manipulate the algorithms used to create these results.
Search engine algorithms relied on on-site information to determine page rankings. That is, they relied on information that was provided by the webmaster. Things such as meta tags, density and index files. All webmasters needed to do was put in the right keywords in the sufficient density and they would start seeing front-page search engine rankings in no time. The web content providers also started to manipulate source code to get clients higher rankings. This started to result in SERPS becoming unreliable and spam ridden pages who's keyword tags did not accurately represent the actual content of the page.
The 1st 'crackers' appeared around 1997. Being able to decode a search engines algorithm (which back then was quite possible), unscrupulous webmasters could get sites into the top 10 as their will. In 1997 several SEO providers decoded Excite's algorithm to its full extent of 35 parameters.

2. A Star is Born.
The heavy reliance of on site factors such a keyword density, which could be (and was being) directly manipulated by webmasters to control their rankings had gotten many search engines into trouble. To offer useful search results to internet users, search engines had to alter the way in which ranking of pages, that actually were relevant and offered useful content was performed. More complicated algorithms had started being developed that took into account off-site factors, such as directory age and link popularity to determine rankings. The cracking of search engine algorithms became a harder and sophisticated task.
At this time the head of the search engine pack was Alta Vista with the balance split between Lycos, MSN, Yahoo and InfoSeek. All of these still exist today but are (as we know) less popular. InfoSeek and AltaVista have offloaded their search, both of which are now 'powered by Yahoo!'.
Even though algorithm had improved. black hat SEO's were still manipulating them and site theft and page jacking was rampant. On September4 1998 Google was founded by Sergy Brin and Larry Page. Google's algorithm 'PageRank', determined site rankings by measuring the quanity & quality of the inbound links. Google's superior, relevant search results immediately attracted a loyal bunch of followers and the competing search engines began to realize how important it was to keep up with Google's new page ranking approach.
The new millennium dawned and Google was solidifying its leading position and fast becoming the de-facto search engine. The former front runners were just as fast becoming internet history. In fact by 2001 Excite, Lycos, AltaVista and Hotbot were all but abandoned by users.

3. The Age of Google.
Its 2004 and 3 top search engines remain; MSN (now Bing), Yahoo! and of course Google. The era of keyword spamming is over. These remaining three start incorporating page ranking factors into their algorithms. Content providers and webmasters now have to rely on being creative to promote and generate links to achieve long term increases in search engine rankings.
By 2005 Google starts taking into account a users search history to come up with personalized search results when logged in. Then 2 years later Google starts a campaign against paid links that affect Pagerank. Another 2 years on and the company announces it will attempt to stop the effects on Pagerank from "nofollow" links.
In todays time, SEO is for the most part, a conversation with Google search. The search engine has over 70% of the market and is the place you have to be seen, if you intend driving any worthwhile amount of organic traffic. Search engine optimization Campaigns are far more labor intensive and complex now than they were a decade ago, but this is good thing from a quality perspective. Searchers get better, more relevant search results and providers actually have to provide value in order to get higher rankings on the results pages.