The first thing that search engines do in order to find pages on the internet is to write “spiders,” which are automated programs also known as “bots” that “crawl” the web by starting with a “seed” set of websites. They’ll crawl out from there looking for all the pages that those websites link to. They then use those links to find the structure of the internet and to discover all the pages on the web, because the web is highly interconnected.
After they crawl the web, they need to build an index of these documents by doing what is called a keyword inverted index, which means that they store all the documents by the terms and phrases that appear on them or that they think are relevant to them.
Once they have got the indices, they calculate what is known as a query independent matrix, which is basically how they rank the webpages based on other attributes other than just relevance to the search query. For example, inbound quality links or social media signals.
In short, SEO is about trying to get as close as possible on the “food chain” to those “seed” websites. The basic process of SEO is actually quite simple in theory; it’s about getting your site on the indices and then being able to rank as well you possibly can. How do you do this? The following steps are the 4 commandments of SEO:
Those are the basics of SEO.