The term search engine optimization (in English language Search Engine Optimization, in acronym SEO) means all those activities aimed at improving the crawling, indexing and positioning of information or content on a website, by crawlers (also called bots) of search engines (such as Google, Yahoo!, Bing, Yandex, Baidu etc.) in order to improve (or maintain) the positioning in the SERPs (response pages to the queries of the web users).

Thanks to SEO optimization techniques it is possible to improve the positioning (ranking) of a website on search engines and, consequently, to obtain an increase in the volume of organic traffic. SEO optimization can be accompanied or supplemented by differentiation in search engines, an operation that aims to increase direct traffic. The organic results higher in the SERP are more likely to be displayed and therefore to be eventually clicked in a higher percentage by users, than those displayed in the central and lower part of the page.

The SEO activities are many and can be divided into on page (ie on the web page) and off page (activities carried out on elements external to the site) and are based on a long list of ranking signals, called «SEO factors».

Optimization stands out among the SEO activities:

  • of the web server;
  • meta tags;
  • of JavaScript and CSS;
  • of code strings and W3C validation;
  • the structure of the site and the navigation menu;
  • textual content and images on the pages;
  • internal links to the site;
  • the usability of the site;
  • the accessibility of information by search engine crawlers;
  • the source code and structured data;
  • backlinks (links from external sites);
  • images and videos.

The search engine optimization activity includes various technical operations that are carried out both on the HTML code and on the contents of the web pages of the site, as well as on the overall hypertext network of the web domain present in the archives of the search engines.

The quality and quantity of hypertext links from other Web domains, which point to a specific domain, are in fact decisive for the positioning of the domain considered. Therefore, also the activity outside the site is indispensable, usually carried out with link building techniques (guest posting is widespread).

Search engine optimization (SEO) differs from Search Engine Marketing (SEM) in that it has the objective of positioning in the organic SERPs and not in the spaces allocated for Pay per click results (paid advertising campaigns). Furthermore, SEO activities offer results in the short, medium and long term based on the positioning difficulty deriving from the number of competitors; while the effects of Pay per click are instant.

The professional figure specialized in search engine optimization is the SEO (search engine optimizer, which has the same acronym for the activity it carries out).

SEO works in close contact with a team of figures related to the world of web marketing, such as developers, graphic designers, marketing experts in social networks, etc.