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Have you ever wondered, “How does Google know where to look?” Have you searched on Google many times, but never considered this question? The answer to this question is “web crawlers”. They can search the web and index it so you can easily find different items. In the following sections, we will provide a detailed explanation of the issue.

Search various crawlers.

When you use a keyword in a search engine like Google or Bing, this website scans the trillions of pages to create a list of results related to that phrase. Here, questions arise in the minds of curious users: How exactly do these search engines access all of these pages? How do they know how to search for them and produce these results in a few seconds, and show them to the user?

The answer to this question is web crawlers, also known as spiders. They are automated programs, called robots or bots, that crawl across the web to be indexed by search engines. These bots find various websites to generate a list indexed by search engines that will eventually appear in your search results.

Crawlers also create and store copies of these pages in the engine database, allowing you to search for different items quickly. For this reason, search engines often place cached versions of sites in their databases.

How does a crawler work?

In principle, a crawler is like a librarian. It searches for information on the web, categorizes it, and then indexes and catalogs the information so that the crawled data is retrievable and can be evaluated.

The operations of these computer programs need to be established before a crawl is initiated. Every order is thus defined in advance. The crawler then executes these instructions automatically. An index is created with the results of the crawler, which can be accessed through the output software.

The information a crawler gathers from the web depends on the specific instructions it receives.

Website maps and selection

How do crawlers choose to crawl websites? We have to say that the most common scenario is that website owners want search engines to crawl their sites. They can achieve this by asking Google, Bing, Yahoo or another search engine to index their pages. This process varies from engine to engine. Also, search engines often select popular and convenient websites to crawl, in Addition to tracking the number of times a URL links to other public websites.

Website owners can utilize specific processes to help search engines index their websites, such as uploading a sitemap. This file contains all the links and pages that are part of your website. Additionally, this file is typically used to specify which pages are to be indexed.

When search engines have already crawled a website, they will automatically re-select that website to do so. The frequency of updates will vary depending on the website’s popularity and other criteria; therefore, website owners often update their sitemaps.

Hide pages from crawlers.

What if a website does not want some or all of its pages to appear in a search engine? For example, you may not want people to be able to search for a member-only page or see a 404 error page on your site. This is where the crawl deprivation list called robots.txt comes into play. This option is a simple text file, known as a robots.txt file, which tells crawlers which web pages to remove from the index.

Another reason robots.txt is essential is that web crawlers can have a significant impact on website performance. Because crawlers download virtually all of your web pages, they can also slow you down. Additionally, their work schedule requires a prior arrival time before entering without additional notice. If you do not need to crawl your pages, equally, stopping crawlers may help reduce some of your website’s load. Fortunately, most crawlers stop crawling on some pages according to the site owner’s rules.

Metadata Magic

Below the URL and title of each Google search result, you will find a brief description of the page. These explanations are called “snippets”. You may have noticed that the snippets of the pages on Google do not always match the actual content of the websites. This is because many websites have something called a “meta tag”. A meta tag is a custom description that website owners add to their pages.

Website owners often provide deceptive metadata descriptions that make you click on the website. Google also lists additional metadata, such as price and stock levels. This is especially useful for those with e-commerce websites.

Examples of a crawler

The most well-known crawler is the Googlebot, and there are many additional examples as search engines generally use their own web crawlers. For example

• Bingbot
• Slurp Bot
• DuckDuckBot
• Baiduspider
• YanBot
• Sogou Spider
• Exabot
• Alexa Crawler

Your search

Web search is a crucial component of using the Internet. Searching the web is a great way to discover new websites, stores, communities, and interests. Web crawlers visit millions of pages every day and add them to search engines. Finally, we must say that reptiles also have disadvantages, but they are also very valuable to website owners and visitors.