What is a crawler?
A crawler, also known as a spider or a bot, is a tool that browses the World Wide Web in a systematic, automated manner. This process is called web crawling or spidering. Many sites, particularly search engines, use spidering as a means of creating an up-to-date index. Web crawlers are mainly used to index the information on the web pages using algorithms and provide relevant and faster search results.
The crawler starts with a list of URLs to visit, called the seeds. As the crawler visits these URLs, it identifies all the hyperlinks in the page and adds them to the list of URLs to visit. It then proceeds to visit these URLs, which can be re-visited at times to check for updates, changes, and the like.
Moreover, crawlers can also be used for automating maintenance tasks on a website, such as checking links or validating HTML code. Also, crawlers can be used to gather specific types of information from Web pages, such as harvesting e-mail addresses (usually for spam).
Why is a crawler important?
With a fast-growing amount of data stored on the internet, it becomes almost impossible for manual exploration or indexing. That’s where the crucial role of web crawlers comes in. They serve multiple purposes for various types of internet users.
For search engines, crawlers are vital in collecting and indexing the web content to provide quick and relevant search results. They help in keeping the search index updated with the hundreds of millions of websites over the internet.
For digital marketers or SEO specialists, understanding how web crawlers work provides key insights to the SEO (Search Engine Optimization). By understanding this, they can optimize their web pages for better visibility and ranking among the search results.
Types of crawler
Web crawlers are categorized into various types based on their tasks. The most common types include:
- Indexing crawlers
- SEO crawlers
- Data mining crawlers
- Spambots and others
For better understanding, let’s go through each of them.
Indexing crawlers are used by search engines for collecting and keeping an updated index of web contents. Examples include Googlebot and Bingbot.
SEO crawlers are specialized tools used by digital marketers or website owners to gain insights and optimize their websites for search engine rankings. Examples include Screaming Frog and SEMrush Bot.
Data mining crawlers are employed to gather specific data from websites for research or analysis purposes. They might focus on extracting information such as pricing data, customer reviews, or social media mentions.
Spambots and other types of crawlers are designed to perform unwanted or malicious activities, such as harvesting email addresses for spam purposes.
Examples of crawler
Googlebot
Googlebot is the most well-known crawler, used by Google to discover new and updated pages to be added to the Google index. The process begins with a list of webpage URLs generated from previous crawls and sitemaps provided by website owners. As Googlebot accesses these websites it detects links on each page and adds them to its list of pages to crawl.
Screaming Frog
Screaming Frog is a very popular SEO Spider tool that acts as a website crawler. It provides insights into how crawlable a website is from an SEO standpoint. The software creates a crawl map and presents reports on problems like broken links, server errors, duplicate content, missing meta tags, and other crucial SEO elements.
Bingbot
Bingbot is a crawler used by Bing to access and index content from across the web. Like Googlebot, Bingbot also uses an algorithmic process to determine which sites to crawl, how often, and how many pages to fetch from each site.
Handy tips about crawler
Make sure your website is easily crawled
Ensure that your website is well structured and that all content is accessible within a few clicks from your homepage. This makes it easier for the crawler to index your site.
Use Robots.txt file correctly
Robots.txt is a file at the root of your site that indicates parts of your site you don’t want accessed by crawler. Use it correctly to prevent the crawler from indexing unnecessary or sensitive data.
Update content regularly
Having fresh and updated content is another important factor. Crawlers prioritize frequent updates in its indexing and ranking process.
Conclusion
As we move toward an exponentially expanding digital universe, crawlers are becoming increasingly essential for search engines, digital marketers, SEO professionals, and website owners alike. Understanding the functionality and benefits that crawlers offer can give you the competitive edge in the digital space.
Remember, the more crawler-friendly your website is, the better are your chances of being noticed by your targeted audience. So, educate yourself more, and adapt to the ever-evolving digital landscape.
Frequently Asked Questions
How can I check what a web crawler has indexed on my website?
You can use Google’s “site:example.com” search syntax to see what Google has indexed from your website. Replace “example.com” with your actual domain.
How can I prevent a crawler from indexing a specific page on my website?
You can use the “robots.txt” file or the “noindex” meta tag on the webpage you want to exclude from crawlers.
How often do web crawlers visit my site?
The frequency of a web crawler visiting your website largely depends on how often you update your content and the specifics of the search engine’s crawling algorithm.