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In today’s digital age, whenever we need any information – be it a recipe, the latest news, or a product review – we immediately go to Google or some other search engine and search. But have you ever wondered what this search engine actually is, how it works, or how it shows the exact answer to your question within 0.5 seconds?
In today’s article, we will talk in detail about each part of the search engine, what the crawler does, how it reaches the website, how it indexes the page, and how it shows the result according to the user’s search intent. So let’s start without any delay!
What is a Search Engine?
A search engine is a software system that scans billions of web pages available on the internet and shows relevant and useful results whenever a user searches for something.You must have heard names like Google, Bing, Yahoo, DuckDuckGo – these are all search engines.
This work is not done by just one software or tool. There is a very complex system hidden behind it, which has 3 major steps:
- Crawling
- Indexing
- Ranking & Result Display
Next we will explain these three steps in detail.
What is a crawler?
Crawler is an automated bot which is also called search engine bots, spiders or Googlebot. Its job is to:
- Visit every website available on the Internet
- Read the pages, links, images, content inside it
- And send that information to the search engine
A crawler is a kind of surfing robot that constantly searches the web for fresh content and new pages.
If your website is visible on the search engine, then the credit for it goes to these crawlers
How does a crawler come to a website?
A crawler arrives at a website by following some specific steps:
1. Seed URLs
Every crawler already has some non-websites (eg. Google, Wikipedia) that it crawls on a regular basis. These are called seed URLs.
2. Through Internal & External Links
When a crawler visits a site, it checks all the links within that site – whether they are internal (other pages of the same site) or external (pages of another site).
For example, if a link to your site is given on a popular website, the crawler can reach your site from there.
3. Sitemap.xml
You can create a sitemap of your website (which is an XML file).When we create sitemap through sitemap generators of by self then we mention all the URL’s available on website in that. When you submit this sitemap to Google Search Console, the crawler easily understands what content is there in your site and where it should go.
4. robots.txt File
You can allow or disallow the pages that you want to crawl by the bots. Robots.txt is one of the best way to tell bots that this page you have to crawl or not.
How does a crawler index a page?
The next step after crawling is indexing. This is a very important step.
Meaning of Indexing
Indexing means making an entry of the content of your page in the search engine’s database, so that whenever a user searches for something, that page appears in relevant results.
Just like a library keeps a record of every book, as to which book is kept on which shelf, similarly a search engine makes a digital record of every web page.
Before indexing the page what crawler finds
Page Title – Title of the page
Meta Description – Short summary of content
Heading Tags (H1, H2, etc.) – What are the important sub-topics
Content – What is written on the page
Keywords – What terms is the page about
Images & Alt Tags – Image content and their descriptions
Page Load Speed – How fast the site opens
Mobile-Friendliness – Does the page look good on mobile
URL Structure – Clean and SEO-friendly URL
Internal Linking – Does the page have links to other pages or not
Where is the Indexing done?
Google and other search engines store data of billions of web pages, and all this is stored in their data centers. When you search for a query, this system goes into that database and retrieves relevant pages.
How does a search engine understand what a user is looking for? (User Intent)
This part is the most interesting. Users write query in the search bar, for example a user want to buy a mobile pgone under 20000 then he will write like this.
“Best phone under 20000”
“Pizza near me”
“What is crawling in SEO?”
Then every time your intent is different. Sometimes you want to buy something, sometimes you don’t want to know, sometimes you are looking for a location based service.
How search engines understand search queries:
1. Natural Language Processing (NLP)
Search engines use NLP to understand what kind of information you want. Natural Language Processing try to help, understand what human intent is for this query.
2. Search Query Classification
Search queries are divided into 3 categories:
Informational— Knowledge is required (e.g., What is SEO?)
Navigational— Want to go to a specific website (e.g., Facebook login)
Transactional— Want to take an action (e.g., Buy shoes online)
Search engine find out the intent of the query generated by user and then provide the best result;
How do the results appear on the search engine results page (SERPS)?
Following its understanding of the user’s query, the search engine extracts important pages from the index and assigns them a ranking based on a number of specific factors:
- Content Relevance
- Backlinks
- Page Speed
- Mobile Usability
- Domain Authority
- Freshness of Content
- User Experience
The top 10 results are those that are most useful, relevant and trustworthy.
Let’s Understand it With Example
If you search – “How search engine works”
Then the search engine will identify keywords:
- “How to”, “chocolate cake”, “at home”
- Then it will see in which pages these keywords are used in a relevant way
- Then it will check the content of the pages to see if the recipe is clearly explained or not
- The page that has images, steps, video will get priority
- Then that page will be shown on top in SERP
Conclusion: what did you learn today
A search engine is a software application that returns the best results based on user queries. Crawler is a bot that scans the content of the website. Crawler reaches the website through seed URLs, backlinks or sitemap. Indexing a page means making a record of it in the search engine’s database. Search engine understands the user’s intent through NLP and algorithms. Results ranking depends on many factors like content quality, backlinks, speed, etc.