SEO(Search Engine Optimization), Unlike web development, is not an exact science and impact of specific SEO actions can become visible after days, weeks, months, or sometimes never SEO is quite different than other sorts of web development, where you make a code change, Switch tab to the browser, refresh, and voila: your changes are instantly visible. Search engine’s ranking algorithms change constantly, almost as fast as new Javascript frameworks pop up. These changes are not documented, and in the best case, they are just hinted. SEO practices can be divided into two main categories: on-site SEO, and off-site SEO. On site SEO is a practice of optimizing both the content and HTML source code of a page Off sitete SEO refers to external signals and links elsewhere on the Internet.