The history of SEO optimization (search engine optimization)
The period of appearance and development of search engines - the 1990's.
Then the story begins and SEO.

Initially, the search engines attached great importance to the internal factors of the resource (the contents of the pages, meta tags, etc.), that is, what could directly affect its owners. This has led to the fact that the influence has become many and often irrational.

The bottom line is a poor-quality issue. Later, the search engine Google was able to swing the scales in the direction of external factors, and a great role was played by backlinks, linking and reference weight. Over time, technology and ranking principles have changed, and today, the site of the website in the issuance is affected by many factors.