In order to be able to rank our Websites higher in search engine results pages we need to first understand how search engines work. Once we have an idea of how they work it will be a lot easier for us to optimize and construct our Websites in such a manner that search engines like them.

When a search engine likes our site it will be automatically ranked higher in search engine results but we need to understand- 

 What is the index of the Web?

When you make a new Web site or make any change to your existing website search engines send a program to your Web site. This program is known as Spiders.

What these spiders do is they open up your Website and start fetching and storing data in the search engines' data centers. The data the spiders collect is mainly site tagline headings keywords text content, links and images etc.

The spiders ignore the styling of your site or the CSS  as this process of fetching is called crawling.

the search engine stores all of the important data of every site on the Web in their database. This data as a whole is known as the index of the web.

 Break down of how search engines work:

It all starts with a simple search.

A person opens up a search engine (e.g. Google) and types in a search term(e.g. Groceries). The search engine sends the search term to their software which then searches the index of the web for related pages to the search term.

Usually, there are hundreds and thousands of pages related to the search term. A list of all such pages is made in the search engine software. This list is not visible to the person who made the search.

Now it's time for the search engine to ask questions from all the pages in this list.

Google has more than hundreds of questions. These questions include how many times is the search term used on this page. Are these keywords included in the title, headings, and domain?  And most importantly how many other pages on the web link to this page?

After all these questions the search engine gives a score to every page in this list. This list is now sent back to the search engine of the user who made the search. This list is then presented in descending order.

Highest score on top and so on. All of this happens in two seconds approximately.