Web Crawler: How it Works and Examples

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Who of you here is managing the business? Has your business developed into an online business? In fact, now online business is one of the best efforts to make your business more developed, you know! What's more, if you don't have a website yet, you will lose the opportunity to get more leads.

However, if you have online your business and have a website, do you know that behind the website, there is a world "unseen by the human eye" where web crawlers play an important role. What are web crawlers? Come on, see more below!!!

What is Web Crawler and its Types?

What is Web Crawler and its Types

Web crawling is an activity of indexing and downloading data (content) from the internet, which will then be stored in the database of a search engine. This web crawling is carried out by a program or system which is usually called web crawlers, web spiders, spider bots and web bots.

Every search engine must have a web crawler whose job is to collect and archive (index) all the information data sought by users. This data indexing activity will enable every search engine user to get the information they need. Further explanation of how web crawling works is in the next point.

Now you are starting to know what web crawlers are. Web Crawlers are actually not just search engine bot spiders. There are several types of web crawling that you should also know about, including:

1. Social Media Crawling

Not all social media allows for crawling, because some types of crawling can be illegal and violate data privacy. However, there are some social media platform providers that are open to this, for example Twitter and Pinterest. They allow the spider bot to scan the page if it doesn't reveal any personal information.

2. News Crawling

With the advent of the internet, news from various parts of the world can be accessed quickly. To retrieve this data from various websites can certainly get out of hand.

There are many web crawlers that can overcome this. The crawler retrieves data from new, old, and archived news content, to read RSS feeds. These crawlers scan information such as publication date, author name, main paragraph, headline, and language of the news content.

3. Video Crawling

Watching a video is much easier than reading a lot of content at once. If you embed YouTube videos, Soundcloud, or other video content on your website, that content may also be indexed by some web crawlers.

4. Email Crawling

Email crawling is especially useful for generating leads because this type of crawling helps scan email addresses. However, it should be noted that this type of crawling can be illegal as it violates privacy and cannot be used without the user's permission.

5. Image Crawling

This crawl type is applied to images. The internet is filled with visual representations. Hence, this type of bot helps users to find relevant images out of millions of images present in search engines.

How do Web Crawlers Add Information to an Index?

How do Web Crawlers Add Information to an Index

A web crawler, also known as a web spider, spider bot, web bot, crawler, is a computer software program used by search engines to index web pages and content on each website.

Indexing is quite an important process because it will help users quickly find relevant queries. You can compare this indexing itself to indexing a book, where you will find an index with a list of questions in alphabetical order and the page that mentions them in the textbook. 

The same is applied in the search index, but instead of page numbering, the search engine will display several links where you can find or find answers to your questions.

How do Search Engines Work Step by Step?

Before delving deeper into how crawler robots work, let's first get to know how the search process on search engines is carried out until a user gets an answer to the question they are looking for.

For example, if you search for “What is Black Hat SEO vs White Hat SEO” and hit enter, the search engine will display a list of related pages. Usually search engines will take the following steps before displaying information to users:
  1. Web spiders will crawl the content contained on the website.
  2. After that the page will be indexed in search engines.
  3. The search algorithm ranks the most relevant pages.

How do Web Crawlers Work Step by Step?

There are lots of search engines that you can choose from. You can also read the following best and fastest browser articles to find out some of them. Each of these search engines in fact uses a web crawler that functions to index pages.

Usually, they will start the process of crawling or crawling starting from popular websites first. The purpose of this web bot itself is to convey the essence of each page content. So that the web spider searches for words on this page and then makes a list which will later be used by the search engine at a later time when the user wants to find information about the website's query.

All pages on the internet are connected by hyperlinks, so website spiders can find these links and follow them to the next page. That is why internal links for a website are very important to make it easier for spider bots to index each website page.

Then, web spiders will send the information they have captured as a search index, which is stored on servers around the world. The crawling doesn't stop after the page is indexed. Search engines periodically use web spiders to see if any changes have been made to a page. If there is a change, the search engine index will update it.

Web crawlers from search engines will crawl each keyword searched for. From these keywords, the system will immediately search the entire internet and databases to display search results for websites that are relevant to these keywords.

The following is the process or how a web crawler works:

  • Keywords are entered into the search engine bar. For example, the keywords entered are "What is the millennial market?".
  • After pressing the "Enter" keyboard, the bot system will immediately search (crawl) all information on the internet and databases.
  • Every website found from search results will be indexed.
  • The system or program will see which websites are most relevant to the keywords.

Is an Example of a Web Crawler?

Is an Example of a Web Crawler

Most popular search engines have their own web spiders which use certain algorithms to collect data about web pages. Web crawler tools can be desktop or cloud based.

The following are several examples of Web Crawlers from various search engines in the world. Many search engines use their own spider bots. Here are some examples of web crawlers, including:

1. DuckDuck Bot

DuckDuckGo is probably one of the most popular search engines that doesn't track the history of its users and follows them on any site visited. DuckDuck Bot web crawler helps find the most relevant and best results that will satisfy user needs.

2. Baiduspider

This crawler is operated by a Chinese search engine called Baidu. Like other bots, Baiduspider crawls through various pages to index content in search engines.

3. Alexabot

Amazon's web crawler, Alexabot is used to identify content on websites as well as backlinks. If you don't want these bots to know some personal information, you can exclude Alexabot from crawling your website.

4. Exabot

French search engine Exalead uses Exabot for content indexing for inclusion in search engines.

5. Yahoo! Slurp Bot

Crawlers owned by Yahoo, Yahoo! Slurp Bot, is used to index web pages to improve user-tailored content.

6. Yandex Bots

Yandex Bot is owned by the largest search engine from Russia. You can also exclude this crawler from indexing content if you don't plan to enlarge your website name in that country.

7. Bingbots

Bingbot is one of the most popular web spiders supported by Microsoft. Bingbot helps the search engine, Bing, to create the most relevant index for its users.

8. Facebook External Hits

Facebook also has a dedicated crawler. For example, when a Facebook user wants to share a link to an external content page with other users, the crawler will scrape the page's HTML code and provide the two users with titles, tags, and images in the content.

What is the Meaning of Googlebot?

Googlebot is the most widely used web crawler today. As the name suggests, this web crawler belongs to Google.

Googlebot collects various documents on a website to create an index that can be searched by the Google search engine. This web crawler refers to two types of web crawlers, namely desktop crawlers and mobile crawlers.

As explained above, almost all search engines have their own spider bots, and Google is no exception. Googlebot is a custom crawler for the world's most popular search engine, Google. Googlebot is used to index content on Google.

How does Googlebot Works?

How does Googlebot Works

Googlebot has two main types, namely desktop bots and mobile app crawlers. Googlebot uses the same crawling principles as other web spiders, such as following links and scanning content available on websites. 

The process is also fully automated and repeatable, meaning you can visit the same page multiple times at irregular intervals. For example, when you are ready to publish content, Google's crawler will take days to index it.

However, you can manually speed up the indexing process by submitting an indexing request via Google Search Console. If your website is not connected to Google Search Console, you can read the Guide to Registering Websites in the following Google Search Console.

You can use robots.txt to “give instructions” to web spiders, including Googlebot. There you can allow or disallow crawlers to visit certain pages on the website. However, keep in mind that these files can easily be accessed by third parties. They will see which parts of the site you have restricted from indexing.

What is the relevance of a website?

The standards for whether a website page is relevant or not are seen from the following various factors.

1. Regular Visits

Every website that has been indexed by web crawling will be frequently visited by the system to see whether there is the latest content from each website. This is done so that the system can ensure that the search results displayed are only the most recent website pages from a website. 

If a website is detected that is not actively updating their website pages, it is likely that the website will not be displayed.

2. Comply with Robots.txt

Robot.txt is a file that is owned by every website, where the file contains information about which pages on the website can and cannot be indexed. Web crawlers will look at this file to determine whether the website will be displayed or not on the search engine results page.

3. The Importance of a Website

The website pages that the web crawler will display on the search results page (SERP) are website pages that have a large number of visitors or have high traffic. A large amount of traffic indicates that the website page is useful to users.

Therefore, every time a user searches for these keywords, the web crawler will display the website with the most traffic. The amount of traffic is important, but what is more important are the keywords contained in the website pages. If the keywords searched for are relevant to those on the website, then the website will be displayed.


Website crawlers are an important part of search engines which are used to index and find content. Many search engine companies have their own bots, such as Googlebot which is backed by Google, and Bingbot by Microsoft.

In addition, there are several types of crawling that are used to meet user needs, such as crawling in the form of videos, images, to social media. Having a good website with optimal speed is clearly one of the factors that makes it easier for crawlers to scan the content on it.

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