How does google and other search engines work

If you ever have used a search engine like Google or Baidu or Bing; and i bet you already have thought at least for once or asked yourself  "how do search engines work ?" if you have ever did so, this is the perfect article you should be reading. so without making it any longer we're going to start explaining.

First what are search engines 

In short a search engine is a software that accesses the Internet and searches in a database of information and gives back a list or results sorted to match what's the user is trying to find. The most popular and used search engine nowadays is Google.If you already have the website URL or link you are not going to need them anyway.So now after knowing what are search engines you're probably wondering how they work...

How do search engines work 

Before search engines they give you the results they go through some processes

Crawling

Crawling is a process that search engines like google scan a website and to find and collect details about each page like page titles, the images used on it, the keywords it has,or even other linked pages... etc. It also keeps getting updates of the content on the web, such as new sites or pages or changes that was made to existing sites, and dead links.
They scans pages completely and stores the links found their and adds them to "next page to visit list" and keeps doing that until it is done... it even visit past pages to check any updates or changes there. Website owners can give those crawlers instructions to help them or to block them using the Robots.txt file,
Google never accept payment to crawl a website more... 

This is a picture that summaries everything : 

Indexing

Simply search engine indexing is the processing of the content of the web pages that the search engine got from crawling . Indexing the step that comes just after crawling that Google like the other Search Engine notes something everything it has  found on a web page from keywords and images to headings and links...etc. Google search Index stores each word it finds on a web page and in a big database of billions of pages.

Ranking

When Google or the search engine completes crawling and indexing, if the user writes any thing in the search bar in a fraction of second the search engine shows results orders the results by the most relevant to the least relevant. Google does know what website is more relevant looking if the searched keywords exists in the website page title and description or in heading tags (from h1 to h6) or on the website content (or the article) or even on the URL of the page, in addition if the website getting back-links from high authority websites it would be very helpful to a page to rank better (back-links are incoming links to a web page). Google have more than 200 ranking factors and it keeps comparing webs pages for the given keyword. If a web page has the most ranking factors the search engine will give them a good ranking position.

A summary :

So in short Google and other search engines simply search the web for content related to the search. then takes results to store and organize them. If the web page is in indexed, it shows results ordered  by the most relevant to the least relevant.