Crawling and Indexing: The Engine Behind Search Insights

Chapter 2 Unit 2: Crawling and Indexing

Crawling & Indexing The Engine Behind Search Insights

After completing this unit, you will be able to:

  • Describe the role of bots in crawling & indexing web pages.
  • Implement best practices for creating & submitting XML sitemaps & robots.txt files.
  • Troubleshoot common issues that affect crawling & indexing.
  • Analyze your site’s crawlability & indexability using various tools & methods.
  • Optimize your site for faster & more efficient crawling & indexing.

In the world of search engine optimization (SEO), two of the most crucial processes that determine the visibility of your website on the search engine result pages (SERPs) are crawling & indexing. Without a comprehensive understanding of these concepts & how they work, it can be challenging to effectively optimize your website for search engines.

What is Crawling?

In the context of SEO, crawling refers to the process through which search engine bots, also known as spiders or crawlers, traverse the internet to find & analyze new & updated content.

It’s akin to a librarian scanning every book in a library to know what’s in them.

This content can come in many forms – it could be a webpage, an image, a video, a PDF, or anything else that can be found on the internet.1

The bots start by crawling the pages of a website & then follow the links on these pages to find other pages on the same website or other websites. As they discover these pages, they use algorithms to decipher & categorize the content. They also consider the website’s overall structure & the individual pages’ interconnectedness.

What is Indexing?

Indexing is a process used by search engines to organize information before a search to enable fast responses. It involves scanning & storing data from websites to a database. For instance, Google’s indexing involves crawling websites, understanding their content, & storing it in the Google index, like a library’s catalog for quick book searches.

During indexing, the search engine analyzes the information it has crawled & makes sense of it. The search engine pays attention to several factors, including but not limited to:

  1. The overall quality of the content
  2. The relevance of the content to search queries
  3. The structure of the content
  4. The presence of keywords
  5. How fresh or updated the content is

Remember that not all crawled pages make it to the index. The search engines have specific algorithms & criteria that determine which pages are indexed & which are not.

SEO Rules for Crawling and Indexing

To enhance your site’s visibility in search engine results, it’s crucial to make it easy for search engine bots to crawl & index your site. Here are some fundamental SEO rules to follow:

1. Ensure Your Site’s Accessibility: Search engine bots need to be able to access & traverse your website easily. Make sure your site’s server is reliable & the site’s robots.txt file is not blocking crucial pages.

2. Utilize XML Sitemaps: Sitemaps act as a roadmap of your website that leads search engine bots to all your important pages. Sitemaps can be especially helpful if your site is hard to navigate, or if some pages are not linked to others.

3. Use SEO-Friendly URLs: Your URLs should be easily understandable, both for users & search engine bots. Using relevant keywords & maintaining a simple structure in your URLs can help in this regard. Our suggestion here is that you must have that keyword in your URL that you want to rank for.

4. Pay Attention to Link Structure: The way pages link to each other within your website, often referred to as the site’s link structure or architecture, plays a crucial role in how search engine bots crawl & index the pages. Aim to create a structure that allows bots to find all your pages within a few clicks.

5. Avoid Duplicate Content: Duplicate content can confuse search engine bots & lead to issues with indexing. Use canonical tags to let the bots know which version of a page you want to be indexed. Before publishing content, make sure to check whether your content is duplicate/rewrite/plagiarism free & then publish. In this case, Grammarly or Copyscape can be used.

6. Keep Your Content Fresh: Regularly updating your content signals to search engines that your website is alive & offering up-to-date information. This encourages more frequent crawling & improves your chances of ranking well.

Topic 1: Role of Bots in Crawling and Indexing

As search engines strive to deliver the most accurate & useful results to their users, they heavily depend on mechanisms like crawling & indexing. These processes are made possible by search engine bots, also known as spiders or crawlers.

These digital entities have a fundamental role in shaping our online experiences. Now, we will delve into the intricate world of search engine bots & explain their role in crawling & indexing web content.

What Are Search Engine Bots?

Before we delve into the roles of bots in crawling & indexing, let’s first clarify what search engine bots are.

“Search engine bots, or spiders, are automated software that crawl the web to index or update a search engine’s database. For instance, Google’s “Googlebot” scans new and updated pages, examining content and links, to determine a page’s relevance for specific search queries.”

In the context of search engines, these bots are designed to visit, or ‘crawl’, web pages & collect data, which is then ‘indexed’ for later retrieval when relevant queries are made on the search engine.

Search engine bots, such as Google’s Googlebot, Bing’s Bingbot, & others, are the digital explorers of the internet. They systematically browse the web, following links from one webpage to another, collecting & organizing information along the way.

The Role of Bots in Crawling

Crawling is the process through which search engine bots discover new & updated content on the internet. This includes various types of files, such as web pages, images, videos, PDFs, etc. The bots start the crawling process with a list of web addresses from past crawls & sitemaps provided by website owners.

The bots visit these addresses, called URLs, & use the links within these pages to find other pages. As they discover these pages, they decode the code within them & store selected pieces of the pages in their vast databases, which are later recalled when needed for a search query.

Crawling is not a one-time job but a complex, ongoing process. Bots continuously revisit websites to check for new additions or changes to the existing content, ensuring that the search engine’s results are up to date & relevant.

The Role of Bots in Indexing

Once the bots have crawled a webpage & collected the necessary information, the next step is indexing. Indexing is the process of storing & organizing the information collected during the crawling process. When a bot visits a webpage, it creates a sort of ‘snapshot’ of the page’s content, including the text, images, & other elements. This snapshot is then stored in the search engine’s index, a vast database of all the web content the bots have discovered.

The index is like a massive library containing copies of every webpage that bots have crawled & deemed good enough to serve up to searchers. When a search query is made, the search engine algorithms sift through the index to find the most relevant pages. It then orders these pages based on hundreds of ranking factors & presents them to the user in the most relevant search engine results pages (SERPs).

The Symbiosis of Crawling and Indexing

The processes of crawling & indexing are tightly interconnected. They rely on each other to ensure that the search engine results are accurate, timely, & relevant. The bots must continuously crawl the web to find new content or updates to existing content. The data collected through crawling must then be efficiently indexed so it can be quickly & accurately retrieved when needed.

In a nutshell, search engine bots are the lifeblood of any search engine. They ensure the engine’s results are reflective of the current state of the internet, providing users with the most useful & relevant responses to their queries.

Their role in crawling & indexing web content is, therefore, of paramount importance to the functioning of search engines & our everyday online experiences.

Topic 2: XML Sitemaps and Robots.txt

Search Engine Optimization (SEO) largely hinges on how well search engine bots can crawl & index a website. This is where XML Sitemaps & Robots.txt come into play. Both of these components are pivotal in directing & guiding search engine bots to better understand the structure & content of a website.

This article aims to provide a comprehensive understanding of XML Sitemaps & Robots.txt, their importance, & how to properly utilize them.

XML Sitemaps

XML Sitemaps are a crucial tool in your SEO toolkit. They serve as a roadmap for search engines to understand the structure of a website.

What are XML Sitemaps?

An XML (Extensible Markup Language) Sitemap is a file where you can list the web pages of your site to tell search engines about the organization of your site content.

“XML Sitemaps are files that list URLs of a website to inform search engines about the site’s structure. They’re like a roadmap, guiding search engines to all key pages on a site, even if internal linking isn’t perfect. For instance, an online bookstore would use a sitemap to ensure search engines find all book listings.”

XML Sitemaps are like treasure maps for search engines. They help search engines like Google explore & understand all the nooks & crannies of a website. Just like a map helps you find your way in a new place, XML Sitemaps guide search engines through the different pages & sections of a website.

It’s like giving them a cheat sheet to quickly find all the important stuff.

Importance of XML Sitemaps

XML Sitemaps are especially important for:

  • New websites: For a website that is just starting out & has few external links, an XML Sitemap helps search engine bots discover & index your pages.
  • Large websites: For larger websites, especially those that frequently add new pages, an XML Sitemap ensures that new content isn’t overlooked.
  • Websites with rich media content: Websites with video or images can provide additional details in the sitemap, such as a video duration or an image subject matter, helping to improve the indexing of this content.

To master “How to Create Sitemap” read our Comprehensive Article


Robots.txt is another vital element of a robust SEO strategy. It plays a different but equally important role to that of XML Sitemaps.

What is Robots.txt?

A Robots.txt file is a simple text file that webmasters create to instruct web robots (typically search engine robots) how to crawl & index pages on their website.

“Robots.txt is a text file webmasters create to instruct web robots (typically search engine robots) on how to crawl pages on their website. For instance, if a website doesn’t want a search engine to crawl a certain page, they would put that page’s URL in the Robots.txt file, such as “Disallow: /private_page.html”.”

It is part of the Robots Exclusion Protocol (REP), a group of web standards that regulate how robots crawl the web, access & index content, & serve that content up to users.

Importance of Robots.txt

The Robots.txt file is a powerful tool that can:

  • Control crawl budget: By telling search engines which pages not to crawl, you can ensure that search engine bots are not wasting time crawling irrelevant or duplicate pages, such as admin pages or certain archives.
  • Prevent indexation of certain pages: There are parts of your website that you might not want to appear in search results. For example, if you have a test site where you can test new features before implementing them on your real site. You can use the Robots.txt file to prevent search engines from indexing these pages.
  • Prevent overloading your server: Too much crawling by search bots can affect your server’s performance. Using Robots.txt, you can limit how much they crawl, preventing them from slowing down your site.

To master “How to Create Robots.txt” read our Comprehensive Article

Combining XML Sitemaps and Robots.txt

While both XML Sitemaps & Robots.txt serve different functions, they are often used in conjunction with each other to guide search engine bots effectively.

Usually, the location of the XML Sitemap is specified within the Robots.txt file. This makes it easier for bots to find the sitemap &, as a result, crawl & index all the pages you want to crawl & index together.

On the other hand, using Robots.txt, you can restrict bots from accessing specific sections of the site you don’t want to be crawled or indexed. This way, the Robots.txt works as a gatekeeper, controlling the accessibility of bots, while the XML Sitemap works as a guide, directing bots to the important pages.

Topic 3: Factors Affecting Crawling and Indexing

As already stated, crawling & indexing are two pivotal processes that govern the way search engines operate. They are responsible for how search engines find, comprehend, & store information from various web pages. While the concepts of crawling & indexing are already understood, let’s delve deeper into understanding the multitude of factors that can impact these processes.

1. Website Architecture

A website’s architecture plays a significant role in its crawl ability. Websites designed in a way that enables search engine bots to easily navigate, find & index content are more likely to have a higher crawl rate.

Hierarchical & logical site structures that incorporate a well-defined URL structure, breadcrumbs, & XML sitemaps can significantly enhance a website’s crawl ability & indexation.

2. Website Size

The sheer size of a website can influence the frequency of crawling.

Larger websites with more pages are typically crawled more often, as there is more content for search engine bots to discover. However, it’s important to note that having a large website does not necessarily guarantee better indexing. The content must still be valuable & well-optimized.

3. Content Quality

Search engines prioritize indexing high-quality, unique, & relevant content. If your website contains copied, repetitive, or thin content, the bots may perceive it as low-quality, which may hinder the crawling & indexing process.

Regularly updating the website with valuable content can also attract bots, signaling that your website is actively providing fresh information.

4. Page Loading Speed

The time it takes for your web pages to load can impact crawling. Faster websites are easier for search engine bots to crawl because they can access & index more pages in a shorter period. A slow loading speed, on the other hand, can hamper the crawling process & lead to fewer pages being indexed.

5. Use of Robots.txt File

The robots.txt file provides directions to search engine bots about which parts of your site to crawl or not to crawl. Proper use of this file is crucial in directing crawler resources towards the most important pages on your site & avoiding unimportant or sensitive pages.

However, improper usage of robots.txt can accidentally block important pages from being crawled & indexed, so handle it with care!

6. Internal Linking

Internal linking helps crawlers discover new content/posts/pages on your website. Well-implemented internal linking strategies make it easier for search engine bots to understand the connections between different pages on your website, thereby improving the overall crawlability & indexability.

7. Mobile Responsiveness

In an era where mobile search is prevalent, search engines consider mobile responsiveness as an important factor. Websites that are not mobile-friendly may face difficulties in being crawled & indexed, especially considering Google’s shift towards mobile-first indexing.

8. Server Errors

If your website is frequently down or experiences server errors, it can significantly affect the crawling & indexing process. Search engines are less likely to index pages from unstable websites, as they strive to provide a seamless user experience.

Therefore, it’s crucial to use a reliable & high-performing server to ensure your website is always accessible for crawling & indexing.

9. Use of Noindex and Nofollow Meta Tags

Noindex” & “nofollow” are two important directives that you can use to control how search engines crawl & index your site. A “Noindex” tag tells search engines not to index a particular page, while a “Nofollow” tag instructs search engines not to follow links on a page.

These tags should be used judiciously to guide crawlers & to prevent them from indexing unnecessary or sensitive pages.

10. Website Security

Search engines prefer secure websites, & HTTPS has become a ranking signal for Google. Therefore, websites using HTTP may be subject to fewer crawling & indexing issues than those using HTTPS.

11. Frequency of Content Updates

Search engines aim to provide users with the most relevant & current results. As a result, they tend to favor websites that are frequently updated with fresh & relevant content.

Regularly updating your website signals to search engine bots that your website is active & has new information to be indexed.

Our advice is to update your site’s old content at least every 3-4 months in addition to publishing content on a regular basis.

Consequently, this can prompt the bots to crawl your site more frequently.

12. HTML Validation

HTML errors can hinder search engine bots from correctly interpreting your website content. It’s important to regularly validate your HTML to ensure that there are no significant coding errors or issues that may impede the crawling & indexing process.

13. JavaScript Usage

While search engines have become more proficient at crawling & indexing JavaScript-based content, complex or improper implementation of JavaScript can still pose challenges to search engine bots.

It’s important to ensure that your key content & navigation are accessible without JavaScript, or at least follow best practices for JavaScript rendering & SEO.

14. Duplicate Content

Search engines strive to index & serve unique content to users. Therefore, websites with any duplicate content may experience decreased crawl rates.

To avoid this, ensure your website provides original & unique content, use canonical tags where appropriate, & handle pagination properly to signal to search engines which content is most relevant.

15. Redirects

Excessive redirects can slow down search engine crawling & indexing. Each redirect takes time to process, limiting the number of pages that can be indexed.

Additionally, not all page rank is passed through redirects, resulting in potential loss of indexing power for your pages. This can be compared to taking a detour on a road trip; the more detours you take, the longer it takes to reach your destination.

Similarly, excessive redirects on a website can slow down search engine crawlers & potentially diminish your website’s visibility & ranking power.

Remember, it’s important to keep redirects to a minimum & ensure they are necessary for a smooth user experience.

16. XML Sitemap

As already stated, an XML sitemap is essential for guiding search engine bots. It provides a roadmap to all the important pages on your site, helping bots to find & index content that may be overlooked during a regular crawl. A correctly structured & up-to-date XML sitemap can thus significantly improve your site’s crawl ability & indexability.

17. User-Generated Spam

Spammy or low-quality user-generated content, such as in comments or forum posts, can negatively impact how search engines view your site.

Ensuring you have moderation processes in place to handle user-generated content can help maintain the quality of your site & not dissuade search engine bots from crawling & indexing your pages.

18. URL Structure

A clean & logical URL structure can enhance both user experience & SEO. URLs that clearly indicate the page’s content help search engines understand what the page is about & how it fits into your website’s overall structure.

Moreover, URLs should ideally be short & devoid of unnecessary parameters, as convoluted URLs can pose difficulties for crawling.

19. HTTP Status Codes

HTTP status codes inform search engine bots about the status of a webpage. Codes like “200 OK” indicate that a page is functioning correctly, whereas “404 Not Found” signifies a missing page. Ensuring the correct use of HTTP status codes is critical, as incorrect codes can cause confusion for crawlers & lead to indexing issues.

20. Pagination

Pagination can influence how crawlers interpret your site. If not handled correctly, crawlers may regard each paginated URL as a separate page, leading to perceived duplicate content. Use of rel=”next” & rel=”prev” links, or combining them with a view-all page, can help search engines understand the relationship between paginated pages.

21. Quality of Outbound Links

Outbound links play a crucial role in determining the reputation of your website. Just like you choose your friends wisely, you should also be careful when linking to other websites. Imagine you’re attending a party, & you introduce your friends to others. If you introduce them to trustworthy & respectable people, you’ll be seen as reliable too.

If you link to spammy or low-quality sites, search engines might think your site is untrustworthy. This can harm your site’s visibility & how often search engines visit it.


We have come to the end of this chapter. In this chapter, you have learned the importance of crawling & indexing for SEO. You have also gained an understanding of how to create & submit XML sitemaps & robots.txt files, how to troubleshoot common crawling & indexing issues, & how to optimize your site for better crawlability & indexability.

You are now ready to move on to the next unit, where you will learn how to conduct a comprehensive keyword research & analysis to optimize your web pages for the most relevant & profitable keywords. Stay tuned!


  1. Web crawler – Wikipedia

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