Optimization for search engines is a set of techniques to promote understanding of the theme and content of one or all pages of a website by search engines. These techniques are therefore designed to provide maximum information about the contents of a web page to crawlers of search engines. These robots, arriving on the site, leave an imprint on the server in the log file. Their passage is marked by a "signature" unique to each.
The objective of this process is to guide the positioning of a web page in search results of engines on keywords corresponding to the main themes of the site. It is generally considered that the positioning of a site is good when it is positioned (ranked) in one of the top ten answers of a search on keywords corresponding precisely to its theme. The search engine optimization is one of the professions of the Internet.