Search Engine is also called an Internet search engine. It’s a software system. If you’re looking for any information and you type in the search box. You will get particular information from the World Wide Web in a systematic way on the Google page result.  Search engines have 3 basic functions.

Search engines three basic functionalities are:

  1. Crawling – the websites and documents over internets
  2. Indexing – storing them in their servers for later results retrieval
  3. Ranking – ranking them according to various ranking factors which is the part of the Google ranking algorithm.

Crawling –

  • Search engines organize their crawlers to discover new documents over the internet.
  • Crawlers are software or robot design to find content over the internet like images, web documents, doc, PDF, videos, etc. by visiting the links.
  • Crawlers travel to the internet by jumping links to another link. That’s why we also called them spiders.
  • Crawlers crawling frequency depends on the popularity of the website how frequently they found new content on your website. Less popular websites get a low frequency of crawling.
  • But you can still submit your site map to Web Search Console. If you don’t know about what sitemap is. A sitemap is a list of links to your all webpage’s. The search console will also let you know the other crawling errors on your website.

Most common crawling errors are:

Accessibility issues, Structural issues, Too many redirections of URL and Server issues.

Indexing –

  • Search engines store the content they found in crawling in their huge data centers for later results retrieval. When you enter a keyword or phrases, search engine looking at its pre-stored data and provide quick results to the users.
  • If you want to block a few pages from the search results you can block crawlers by restricting them by uploading a robots.txt file with Disallow command.

Example:-  This is the Robots.txt of very popular news websites. They are restricting the crawler to enter a few directories.

User-agent: *
Disallow: /images/ndtvvideo/*
Disallow: /news/redirect/*
Disallow: /news/feeds/*

Create your own and save this text file to the root directory of your website.


  • Search engines look to satisfy their users by providing quality and accurate results to their searchers. If results not satisfying to their users they might switch to other search engines.
  • Search engines use a ranking algorithm to assign a score to the pages and documents. So, more the score high in the ranking.
  • The algorithm is the set of rules to determine the quality of web documents. These algorithms keep changing from time to time by search engines to improve the search results.

Read more about search engine ranking factors.