What is Crawling in SEO? A Beginner’s Guide to How Search Engines Discover Your Site

What is Crawling in SEO?

Crawling is the process search engines like Google use to discover content, images, videos, and PDFs by following links across the web. Crawlers depend on a logical site structure, clear internal links, and up-to-date sitemaps. If your pages aren’t crawlable, they’re invisible to search engines, no matter how good the content is.

Fun fact: Does it make you wonder why this process is called crawling? Well, it is because crawling bots are also called spiders. Now imagine hundreds of small spiders jumping from one URL to another, filling every page like Jenning’s home in California in the 1990 movie Arachnophobia. 

In this blog, let’s break down crawling in SEO to set a solid foundation for your learning journey. At the end of this blog, you will find the most common interview questions related to crawling in SEO, which we teach as part of our digital marketing course at gyaner. So, keep reading till the end.

How Does Crawling Work?

Crawling, which is the most critical aspect of technical SEO, begins when search engine bots land on your site and move through links to discover more pages and collect data in the process. These bots visit each linked page to gather content and media like text, images, and videos.

Here is a crisp breakdown of how crawling works: 

• • Link Discovery: Bots discover new pages by crawling through internal links on your site and external links from other websites.

• • Content Analysis: They read and assess content, including text and media.                                                        Note that if an URL is a non-text file, such as an image or a video, a search engine will not be able to look inside it nor understand its content. It can however collect metadata, like the information provided in your sitemap about a media file, like a video’s running time, age appropriateness, an image’s location etc. This limited information is enough for the file to be indexed and made available in search results.

• • Page Indexing: After analyzing, the page is added to the search engine’s index for future ranking.

How to Make Your Website Crawl-Friendly

Making your site crawl-friendly means you’re helping Google do its job faster and more efficiently, which leads to better visibility and rankings.

Let’s look at a few ways to make that happen:

1. 1. Create and Submit XML Sitemaps

Use tools like Screaming Frog or Rank Math (if you’re on WordPress) to generate an updated sitemap. Then, log into Google Search Console, go to the ‘Sitemaps’ section, and paste the sitemap URL. This allows Google bots a clear path to your site’s most important pages.

2. 2. Use Robots.txt Properly

Access your robots.txt file through your WordPress SEO plugin or cPanel. Make sure you’re not accidentally blocking key folders like blog or services. After editing, test it using Google’s Robots.txt Tester to be sure Googlebot can reach everything that matters.

3. 3. Avoid Broken Links and Redirect Chains

Broken pages waste crawl budget. Use tools like Ahrefs’ Site Audit or Screaming Frog to find dead links and long redirect chains. Fix them by either updating the URLs or removing them altogether. This helps crawlers move efficiently through your site.

Tools to Track Crawling on Your Website

Catching crawl issues early lets you fix them before they hurt your rankings. The right tools show you exactly how bots see your site, where they get stuck, and which pages they never reach. In the next section, we’ll explore three free or low‑cost tools you can use today to monitor and improve your site’s crawl performance.

Google Search Console

To monitor and improve how Google crawls your site, go to the Crawl Stats and Indexing sections in Google Search Console. Use Crawl Stats to check crawl volume, response codes, and host status. 

In the Pages report under Indexing, identify pages marked as “Discovered – currently not indexed” or “Crawled – not indexed.”

Once you find issues, inspect the affected URLs using the URL Inspection Tool to understand what’s preventing indexing. From there, you or your SEO team should fix the problem, such as crawl blocks, thin content, or missing internal links, before escalating to developers if it’s a technical issue.

Screaming Frog

Download your server’s raw access logs from your hosting dashboard or CDN. Upload them into Screaming Frog’s Log File Analyzer. You’ll see exactly which URLs Googlebot is visiting and which ones it’s ignoring.

If you notice important pages aren’t getting crawled while low-value URLs (like admin or filter pages) are getting attention, it’s time to act. Add internal links to pages that didn’t get crawled or update your sitemap. Block unnecessary URLs using robots.txt to help bots focus on what matters.

Key Terms Related to Crawling That Will Make You Sound Cool in an Interview and Cooler to your Grandpa!

Web Crawler 

A software program popularly known as bots or spiders. They are sent out by search engines to gather information from your site, and follow links. They are the OG surfers of the web. They discover new pages and help them get indexed.  

Seed List

Everything begins somewhere. If you are not so sure of this, go read the first sentence of this blog. That is where it begins :/ Now that you are convinced, seed list refers to the list of URLs that a crawler begins its work with. These are trusted websites that are regularly updated and therefore the crawler knows that it will find something new every time it visits. The crawlers also use the sitemaps submitted by a website administrator as a seed list. 

Crawl Budget

Unlike the spiders in nature, who are mostly chilling in their webs, crawling spiders have a lot to do. A ridiculous amount of work! Therefore, they need to manage their time very effectively. Crawl budget refers to the time crawlers will dedicate to a website to crawl their content before moving on. Smaller websites need not worry about the crawl budget but larger websites with more than 10k pages need to be very mindful of their internal structure and possible errors. 

Crawl Rate Limit 

The highly productive spiders need certain guidelines so that they do not end up over burdening a site with requests. Crawl rate limit prescribes the maximum fetching rate that a crawler should adhere to while working its way through a site. It is the number of simultaneous parallel connections that a bot may set up while crawling a site. A website administrator may also define the time that a crawler should wait in between sending requests. This can be done using the crawl-delay directive in robots.txt file. An administrator can set a limit to Googlebot’s crawling of their website via Google Search Console. 

Crawl Demand

Crawl demand refers to how often a search engine bot wants to crawl your website. If your page receives less traffic from its rank in the search engine, your crawl demand will be less. The more popular your site is the higher the crawl demand will be. Updating your site regularly will increase crawl demand while having stale URLs, a slow site and too many links leading to error pages will decrease the crawl demand. 

Infinite Spaces

While on an E-commerce site you must have noticed that there are filters based on colour, size and prices. The site is going to show you a different search result based on the filters you have applied (known as faceted navigation or filtering). These are alternated pages and an e-commerce site can have thousands of them. These result in the creation of a large number of links within a site that provide little information to search engine crawlers, and are called infinite spaces. When a crawler encounters an infinite space it may fail to index the real content in your site. This wastes crawl budget and uses up bandwidth, slowing down your site. Google Search Console notifies website administrators when Googlebot encounters infinite spaces. It is imperative that you keep an eye out for them. 

Parameterised URL and Duplicate Pages

Some URLs are parameterised, meaning, a string of text is attached to the end of an URL after the query (?) sign which can help you organise your website. Let’s take a look at an example:

https://www.example-store.com/search?category=shoes&size=10&color=blue

Sometimes, when you use parameterised URL you may end up with duplicate URLs that lead to the same page or if your website is using faceted navigation, may lead the crawler to near duplicate sites that offer no new information to it. This gives rise to SEO issues, irrelevant pages may end up being indexed while your real content gets ignored. Thankfully, when google detects duplicate URLs, it forms clusters of them and chooses the best one to represent in search results. 

Deep Crawling and Shallow Crawling

Most search engines conduct a shallow crawling of websites, meaning, they quickly scan the main pages of a site and the URLs on them. Their main function is to search as widely as possible and as quickly. They often cannot gain all the information necessary from sites having a complex page structure and dynamic elements. Deep crawling fetches more information about pages, even if they are buried under multiple layers. Sometimes, website administrators use deep crawling tools (Screaming Frog SEO Spider, Lumar) to scrape as much information as they can from their competitors, to understand their strategies and come up with counter-strategies. 

Deep Crawling can give rise to a number of ethical issues. The most basic things to remember are the following:

• Your crawler should not overburden a website.
• The information you retrieve should be what is publicly made available and not protected information.
• The information received should not be plagiarised in any way. You should only treat information as facts and not as a commodity that can be stolen. You must not infringe upon copyrights.  
• The tools you use should respect the guidelines laid down by robots.txt files.

Common SEO Interview Questions on Crawling

Below are common interview questions related to crawling in SEO. While covering all the possible questions is out of the scope of the blog, you can use the following questions as a starting point to your interview preparation.