What is a Web Crawler? How does it Work? How Does It Help Both Website Owners and Users?

June 27, 2022

Have you ever wondered how Google knows where to look when you search for anything on the web? The solution is "web crawlers," which search and index the web to make it easier to discover stuff on the internet.

Search Engine and Crawlers


When you're using a search engine like Google or Bing to look for something specific, the site sifts through billions of pages to compile a list of results. How can these search engines keep track of all of these sites, know where to look for them, and produce results in seconds?

Web crawlers, sometimes known as spiders, are the answer. These are computer programs (commonly referred to as "robots" or "bots") that "crawl" or browse the internet to be included in search engines. These robots crawl websites to compile a list of pages that will eventually show up in your search results.

Crawlers also generate copies of these pages and store them in the engine's database, allowing you to do searches very instantaneously. This is also why search engines frequently save expired copies of websites in their indexes.

Web Site Map and Selection


So, how would crawlers determine which sites to visit? The most typical case is for website owners to want their pages crawled by search engines. They can do so by asking for their sites to be indexed by Google, Bing, Yahoo, or another search engine. Engine to engine, this technique differs. Furthermore, search engines typically choose famous, well-connected websites to crawl based on the number of times a URL is linked to other public websites.

Certain procedures, such as publishing a site map, can be used by website owners to aid search engine indexing. This is a text file that contains all of your website's links and pages. It's often used to specify which pages you want to be indexed.

If a website has already been crawled by a search engine, it will be crawled again automatically. The frequency fluctuates depending on a variety of factors, including the popularity of a website. As a result, site owners should maintain their site maps updated regularly to inform search engines about new websites to crawl.

Robots and Politeness


What happens if a website doesn't want part or most of its pages to show up in a search engine? You may not want visitors searching for a members-only page or viewing your 404-error page, for example. This is where the robots.txt file, commonly known as the crawl exclusion list, comes in. This is a simple input file that tells crawlers which websites they should ignore.

Web crawlers may have a substantial impact on site performance, which is another reason why robots.txt is vital. Crawlers use resources and might create slowdowns because they are effectively downloading all of your website's pages.

They show up at inconvenient times and without permission. Stopping crawlers may assist minimize some of the load on your website if you don't require your pages to be indexed regularly? Fortunately, most crawlers follow the site owner's guidelines and cease indexing particular pages.

Metadata Magic


Every Google search result has a brief description of the website beneath the URL and title. Snippets are the names given to these descriptions. You may have observed that the Google snippet for a page does not necessarily correspond to the website's real content. Because many websites employ "meta tags," which are custom descriptions that site owners put on their pages, this is the case.

Site owners frequently create attractive metadata descriptions to get you to visit their site. Other meta-data, such as pricing and stock availability, is also listed by Google. This is extremely important for e-commerce website owners.

Searching the internet is a necessary element of utilizing it. Searching the internet is a fantastic method to find new websites, shops, groups, and hobbies. Web crawlers view millions of sites every day and index them in search engines. While crawlers have certain drawbacks, such as using site resources, they are extremely beneficial to both site owners and users.

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