What Is Web Crawler? And How It Works?

What Is Web Crawler? And How It Works?

There is a huge number of pages on the internet which even the biggest crawler can’t complete the indexing of these pages. So, the engine finds difficulty in giving relevant search information before 2002. Now appropriate information is provided immediately. Just because of an automated system called ‘Web Crawler’. It works like a robot.

If you are not aware about, What is web crawler? This article will help you to understand the basics.

Definition of Web Crawler

Web Crawler also called a spider or bot is a process or system that searches the internet generally for web indexing to provide faster pages search.
The crawler is the technical term which means accessing the internet and getting a relevant appropriate result for your searches through a software program. The main purpose of the crawler is to gather web content.

How does web crawler work?

Running a web crawler is not an easy task. A web crawler is an important module of search engines. Crawler interacts with a large number of web pages which include web server and server name, which are apart from the control of the system. Hence, crawling is a delicate application. The speed of crawler is control via an individual’s internet connection but also through the site of web pages.

There are numerous applications available for web crawling, but the fundamental process of operations is the same, which are as follows

  • Download the web pages
  • Overlook all the downloaded pages and retrieves all the links
  • After that, replicate the process for each link retrieval

A whole website can be crawl using a web crawler through an inter/intranet. Firstly, you have to enumerate a URL and the crawler will go along with all the links found in the HTML pages, leads to more links, and will follow again and so on. The website looks like a tree-structure and the URL is the root. A single URL server has a list of many URLs for a crawler. Web crawlers overlook the particular page and noted down the hyperlinks on that page that signify other web pages. Then that web page will look over, and this process will continue. When a crawler visits the particular web page it extracts the link to different pages.

Also check: Growth Hacking in Digital Marketing.


Search engine website crawler: These types of crawlers are operated by huge farms that spread to countries and continents. The data is accumulating on a server warehouse. In addition to this, Google and other search engines use these types of crawlers. Crawler permits to see, access, and use the data that is collected through certain tools.

Personal website crawler: These types of crawlers are used for personal or business use. They are used for two specific jobs, scraping the data from the search result, and to monitor web pages that are down. On the other hand, these are limited in scalability and operations but you have control over it.

Commercial website crawler: These crawlers are developed for commercial use having specific features, good control, and easy access. A commercial website crawler has a larger number of data. Hence, they come up with the scalable solution required for commercial purposes.


  • Crawlers are mainly used to create links for all the visited pages. Later it processed via a search engine, which indexes the downloaded pages to get fast search results.
  • It used to collect a specific type of information such as an email harvesting address.
  • The crawler uses web analyzing tools to gather data contemplating page view and outbound links
  • Also used to automatically maintain the website, for example, analyzing the links and approving HTML codes. 


Googlebot is the most used Web Crawler on the internet but another more web crawler also available

  • Bingbot
  • Slurp Bot
  • DuckDuckBot
  • Baiduspider
  • Yandex Bot
  • Sogou Spider
  • Exabo

Essentials for WebCrawler

  • Workable: Process and system should be suitable for the various frameworks.
  • High-execution: The process must be scalable for the minimum to the maximum number of pages. So, quality and disk commitment are critical for maintaining high execution.
  • Culpability tolerance: The main purpose is to identify and analyze difficulty like invalid HTML code, and having good communication for rules and regulations. The process should be persistent as the crawling process takes time.
  • Prolongation and layout: There should be an appropriate and accurate tool for monitoring the crawling process like downloading speed, statistics, and administrator to adjust the speed of the crawler.

To sum up, a web crawler is a computer program that browses the internet through a processed and automated manner. It supports the search engine, performing data mining as well.


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