How Crawling and Indexing works in Google Search Alogrithm


Do we have to tell the importance of the search engine nowadays? No, right? You type in any keyword in the search bar of the google, you can see any number of links that suit the keyword you have given just in the matter of seconds. There are lot many search engine, a  software system that is designed to search for information on the world wide web which are giving responses to the billions of queries that a user asks for. In them, one of the most popular ones is Google.

Do you know, how many people use google search? Almost 1.7 billion people actually use google to search. The search engine has really become our other friend in giving us knowledge and any suggestions. It has really become a part of our today’s lives. I have searched the word “keyword” in the google, and I got about 51,10,00,000 results in just 0.45 seconds. We can observe how fast the results come. What we only know, is searching anything that comes in our minds, but we don’t mind in knowing the behind story. There is a lot more action that undergoes behind the scenes.

he main idea behind the Google’s search engine is that the web can be represented as a series of interconnected links, and its structure can be displayed by a complex mathematical graph. Every search engine we have today follows different techniques and methods. Can we just take a moment to appreciate on how challenging and knowledge, today’s engineers are to gather all the information, put them at one place, update and optimize to present changing world and provide the results in seconds when users search? Let us talk about the methods and techniques that are followed by the Google. The techniques that the google are using are Crawling and indexing. These terms are the part of the SEO. The web world entirely depends on this two terms. The steps that are included are,

  • Crawling
  • Index
  • Algorithm
  • Displaying results

These are the main steps of the google search engine. Let us go deep into the topic to learn about these terms,


Crawling is the technical process that tracks down the latest information. In the SEO terminology the term “crawling” means “following your links” using the file called as robots.txt. Crawling is simply defined as following all the links of the web page to fetch information from web pages using the software called “crawl”, which is also called as “spider”, “bot”. This software developed by Google fetches information from web pages. The information that the crawl collects like domain names, URL, descriptions of the data, keywords, images, videos, audios etc. There is any number of sites and pages being generated, is it possible for a human to collect, record and organize them, absolutely no right? these crawlers had made this job easier.

I suppose you have created the new page or website and links to your earlier website main menu, then that work of linking is of crawls. As soon as the bots get the signal about this new page, it visits your page and indexes it. There are few platforms such as WordPress that will alert the search engine automatically above your creating the new page. The crawlers are in the form of “Document Object Model” (DOM) which is written in the HTML and JAVA code. The thing to remember here is, every website you create will not be crawled by the Google, instead, it only crawls the trusted websites that serve proper content.

  • As the crawling process involves of interacting with thousands of web serves, it is considered as the most fragile application.
  • In this application, the spiders or crawlers are used to create a copy of the visited websites and their data links for later processing by a search engine.
  • The crawlers can also be used to maintain the tasks on a website such as, checking links, validating HTML codes etc.

The other application that crawlers are used for is to collect all types of information from the websites, such as the gathering of email addresses just to let know as spams.   

There are few features that the crawler provides


There are few websites that create the “crawler traps”, which are generated that misleads the crawlers in getting trapped fetching any number of pages in a particular domain. So the crawlers are to designed in such a way that they are not affected by such traps.


The web servers have some policies regulating the rate at which a crawler must visit them. So the politeness policies must be respected.


The crawler must fetch the web pages first that are useful without consisting any poor information.


The crawler must be extensible so that it could be adapted to new data formats and protocols.


The performance of the crawler must be efficient and speed.  


The indexing process is a process of creating an index for all the data that is been collected through crawling and keeping them into a giant database from which when the users search for anything, the data from this data is retrieved and shown in the results that are suited for the keyword searched. The index of the google is similar to the index as the book. The google’s index has about hundreds of billions of web pages.

  • Once the webpage is detected by the crawlers, that particular data is stored like said above and indexes in such a way that makes easier when a user searches.

The index is done on the basis of,

  • Accordingly, that is related to the user’s question
  • Ranked according to the relevancy

The index that is made after the crawling process is distributed across many serves to make the searching more efficient. According to the google’s estimation, for every search, 500 servers work together to find the best results.

In the indexing process, all the stored data is categorized into documents based on the individual keywords.

For example, let’s us consider for “Latest songs”

The index(storing of data like in list) is made for separate keywords, it means the index is made for “latest” in documents and “songs” in other documents. When both keywords are searched as one, the results have shown consists of data from both the documents.

Not only storing, the data must also be sorted based on ranking or scoring according to the relevancy of the user’s searched keyword.

Here are some of the factors on which the ranking is based,

  • The page rank
  • Based on authority a trust of the webpage.
  • The recurrence of the keywords, sentences or may be synonyms of the keyword that occurs on the page.


  • The ranking is considered as one of the major areas of the search engine optimization.
  • The next step which is the last step is the displaying the results. Once the crawling and index processes are over, the results are shown on the basis of the user’s search. It retrieves the data from above processes and displays the best-matched results in the browser as per the search query by determining what each website is about and how it should rank. But, there is something you need to do to make your website show in the search engine results. So, for this, you have to make sure search engines can crawl and index your site correctly, otherwise your website content will not be shown in the search results appropriately.

The google always updates the technologies and search algorithms to deliver the best results. The above algorithm is the most complex search algorithm but gives the accurate results. This is the reason, why the google has become a popular search engine as well as the biggest technology company. Now, can we go for other search engines besides the Google?



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