Brief History of search engine optimization (SEO)
Back in the "Wild West" of the internet age of the mid 1990s, websites started popping up faster than people could keep up with them. Search engines were invented to help web users find what they wanted quickly and efficiently.
Back then, all a webmaster had to do to get his or her site indexed was to submit their URL to a search engine. A spider would be sent out to crawl the website, searching for any and all outgoing links as well as relevant keywords to report back to the search engine for indexing. Eventually, people started to see the value in getting higher up in search results, and the term "search engine optimization" was coined.
Since search engine algorithms relied so heavily on backlinks and keyword density, people began to come up with all sorts of ways to trick the system. One notably underhanded technique was the use of link farms. Link farms were networks of websites created with the sole purpose of hosting backlinks. Webmasters and internet marketers would commonly buy and trade backlink space. Search engines responded to such tactics by developing more complex algorithms to determine the relevance of a website. Google PageRank is one such example.
While employing PageRank brought some much needed order to things, Google's subsequent algorithm updates were what made the biggest difference. In 2011, Google released the Panda algorithm update, which lowered the ranking of low-quality websites. In 2012, Google unleashed the Penguin update to penalize websites that violated Google's webmaster guidelines.
Recently, changes made to Google's Webmaster Guidelines provides even more insight into how Google is continuing to work on creating an environment in which natural backlinking is rewarded and unnatural backlinking is penalized. Specifically, the changes addressed concerns about guest posting, article directory marketing, advertorials and more.