Web Crawler

Web Crawler: What Is a Web Crawler and How Does Crawlers Work?

Digital Marketing

Web crawlers are the code behind most search engines. They help you rank your website in Google, Bing, and other major search engines. Web crawlers are also used to index content on the web, which is how they know where to go next when searching for something specific. This article will explain what a web crawler, Its types, how it’s works and why it matters for your site success!

What Is a Web Crawler?

A web crawler is a program that runs across the internet, visiting each website and extracting information. Web crawlers are used to find new or updated pages on a website and crawl through them from top to bottom. They can also be used for other purposes like analyzing traffic patterns, finding broken links or duplicate content pages in your site’s database.

Web crawlers work by following hyperlinks on websites and copy their contents into another file called an HTML index file or “crawl table” which contains details of all pages visited during the crawl process (or at least those which have been found). The index file is then sent back to you so that it can be analyzed by search engines like Google who use this information when ranking websites according to how popular they are based on their content/link popularity etc.

Web Crawler Work

How Does a Web Crawler Work?

A web crawler is a program that can search the internet for new content. Crawlers use a variety of methods to find new content, including:

  • Following links from page to page (the most common approach)
  • Determining whether a page has been accessed by searching for referer logs (a type of HTTP header)
  • Examining HTML source code to see if it matches pages in its database

What Are the Crawling Policy

Crawling policy is a set of rules that define how a web crawler should crawl your website. This can help you control how Google and other search engines crawl your site, which means it’s important to make sure that these rules are being followed.

The following are some of the most common crawling policies:

  • Selection policy
  • Re-visit policy
  • Politeness policy
  • Parallelization policy

List of Web Crawlers

Web crawlers are programs that search the internet for information about websites. These programs are often automated and run 24/7. Web crawlers are responsible for indexing content on websites and making sure that they are properly indexed. If a website does not have proper SEO (search engine optimization), then it could potentially be missed out on traffic from search engines. Here are some web crawlers.

1. Google Bot

Google Bot is the official name given to the search engine spider (crawler) that is used by Google’s web indexing system. It is the first step in the Google search algorithm.

2. Bing Bot

Bing Bot is the official name given by Microsoft to their own web crawling software. It is the second step in the Bing search algorithm.

3. Yandex Bot

Yandex Bot is the official name of the web crawler that powers the Yandex.ru search engine. It is the third step in the Yandex.com search algorithm.

4. Baidu Bot

Baidu Bot is the official name for the web crawler that runs the Baidu.com search engine. It is not the only bot that runs Baidu.com, however it is the primary one.

5. Ask Bot

Ask Bot is the official name assigned to the web crawler that indexes the content on Ask.com. It is the fourth step in the Ask.com search algorithm.

6. Duck Duck Go Bot

Duck Duck Go Bot is the official name that was assigned to the web crawlers that run the DuckDuckGo.com search engine.

7. Sogou Spider

Sogou Spider is the web crawler for the Sogou.com, a leading Chinese search engine that was launched in 2004.

How Does a Web Crawler Know Where to Go Next?

To find new URLs, a web crawler uses a special algorithm. This algorithm is called a hierarchical structure and it’s based on the URL structure of your website. For example, if you have an article on your site that starts with “About”, then the next link will be something like “About Us”, which would lead to another page about your company.

The algorithm works by using an index of all possible paths through the site (e.g., /about) so that when it finds one path it can determine which other pages are located at each level in this hierarchy (e.g., there might be five levels). Once these paths are determined, they’re used as starting points for further crawling efforts—and this process continues until every possible page has been visited!

Types of Web Crawler

Web Crawler is a software that helps search engine optimization (SEO) companies to find out how many visitors they have got on their website. Web Crawler is a tool that crawl websites and indexes them. Once indexed, the data is stored in the database and later displayed to the user. There are different types of web crawler tools available in the market. These tools are used to analyze the content of a website and its keywords.

There are two types of web crawler:

1. Manual Crawling:

In manual crawling, we manually enter the URL of our site and click the submit button. Then the tool will start crawling our website and indexing it.

2. Automatic Crawling:

In automatic crawling, we just need to provide the URL of our website and then the tool will automatically crawl our website and index it.

The following are some of the advantages of using web crawler:

  • We can check how much traffic we get daily, weekly, monthly etc.
  • We can know about the number of pages crawled and indexed.
  • We can check what kind of keywords are being searched on our website.
  • We can track the changes in our website over time.
  • We can monitor the performance of our website.
  • If any error occurs in our website, we can fix it immediately.
  • We can create a sitemap of our website.

Websites are created to make money. So if we want to increase the amount of money we earn, we should use SEO techniques. Search Engine Optimization is a technique that makes sure that our website gets maximum exposure. When people search for something on Google, Yahoo, Bing etc., they first type the keyword in the search box. After typing the keyword, they press Enter. Now, the search engine displays the results based on the keyword typed. If our website contains the keyword typed by users, it shows up in the list of results. That’s how we get traffic to our website.

What Can You Do to Help Web Crawlers Find and Index Your Content?

You can help web crawlers find and index your content by placing it in a place where they can find it. When you make changes to the site, make sure that those changes are reflected in the META tags of your pages.

You should also try to use sitemaps so that search engines know what type of content is on each page. This will help them understand how relevant each page is for their algorithm, which will improve their ranking system when someone searches for something specific about what you’ve written about online (e.g., “how do I get more traffic?”).

Finally, make sure that there’s a good structure behind each piece of information posted on your site; otherwise, search engines won’t be able to properly index all those pages!

Web Crawler spider

Why Are Web Crawlers Called ‘Spiders’?

Web crawlers are often called “spiders” because they’re arachnids, not insects. Spiders have eight legs, not six; their two body segments (the head and abdomen) are fused together in a characteristic way that makes it easy to tell them apart from insects such as ants or beetles.

While spiders don’t fly like flies do, they do crawl along the ground on eight legs with their last pair of legs held up behind them like antennae.

Web Crawlers Are Important for Your Website Success

Web crawlers are important for your website success. Web crawlers help search engines find and index your content, which can increase the number of people who find you through search results. They also help to improve your SEO (search engine optimization) by providing data that helps you rank higher in search results.

Web crawlers help you understand how your website is performing by letting you see which pages are getting traffic or getting indexed by a particular search engine, as well as what types of content are getting clicked on most often by users when they arrive at those pages via their web browsers (this information helps determine if there’s something wrong with those pages).


Web crawlers are an important part of SEO, and they can help your website rank higher in search results when used correctly. Web crawlers are also great for finding new content to link to so that you can increase the amount of links pointing back at your site.

Important Questions and Answers on Web Crawler?

Question: What is a web crawler?

A web crawler (also known as spider) is a program that automatically follows links on websites, indexing them in order to make it easier for people to find information later. Web crawlers are often used by search engines to provide their users with access to a comprehensive list of sites that they have indexed.

Question: Why do we need a web crawler?

Web crawling helps us to understand how the internet works. We use web crawlers to collect data about our favourite websites and then analyse it to learn what’s going on behind the scenes.

Question: How does a web crawler work?

The basic idea behind web crawling is to follow links from page to page until you reach a link that takes you somewhere else. Once you’ve reached that point, you repeat the process again. You keep doing this over and over until you’ve visited every single page on the website.

Question: What are the advantages of using web crawler?

Using web crawlers gives us insight into how websites work and how they’re organized. It lets us know what kind of content is on each page and whether or not it’s relevant. It also tells us if any pages aren’t working properly.

Question: What are the disadvantages of using web crawler?

There are two major downsides to using web crawlers. First, they take time. If you want to crawl a website, you’ll need to sit down and wait for hours before you get anywhere. Second, some websites don’t allow you to visit certain parts of their site. These restrictions may prevent you from seeing things like comments sections, forums, or blogs.

Question: Can I use Google’s web crawler and grab data from any website?

Yes, we can use google web crawlers to get all images and text from any site. But make sure that you have permission to do so.

Question: How many times can I run the same Google’s web crawler?

You can run the Google’s web crawler as much as you want to.

Question: How to use Google’s web crawlers with python script?

Run the code below on Python IDLE.

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