Understanding How Google Crawls a Website for SEO

If you’ve ever searched for something on Google, you probably don’t think about what happens behind the scenes. But before any website appears in search results, a process takes place in the background – and it all starts with SEO crawl.

Crawling is the first and most important step in getting your website discovered. Without it, search engines won’t find your pages. If they can’t find them, they won’t index them. And if your site isn’t indexed? It won’t show up in search results or get any organic traffic.

Now, you might assume Google just finds everything on the internet. But that’s not exactly how it works. Back in 2016, Google announced it knew about 130 trillion web pages. That number has grown massively since then.

Yet, research from Ahrefs shows that 96.55% of all web pages receive zero traffic from Google. That means not every page gets crawled or indexed.

So, how does SEO crawl work? And why do some pages get discovered while others are completely ignored? Let’s break it down.

What is Search Engine Crawling?

Crawling is how search engines like Google find new and updated pages on the internet. They do this with automated bots, often called crawlers or spiders.

These bots move from one page to another by following links, scanning the content they find. If your page is new, a search engine must crawl it first before it can show up in search results.

Imagine a massive library where new books arrive every second. Before those books can be placed on shelves, a librarian has to scan their contents, categorise them, and decide where they belong. That’s exactly what search engines do.

The problem? Not all books (or web pages) make it into the library’s catalogue. Some are ignored. Some are skipped. And some take a long time to be processed.

That’s why understanding how crawling works is so important if you want your website to appear in search results.

How Search Engine Crawlers Work?

Each search engine has its own bot, which is responsible for crawling and indexing pages. Here are some of the major ones:

Search Engine	Bot Name	Purpose
Google	Googlebot	Crawls & indexes web pages for Google Search
Bing	Bingbot	Finds and processes pages for Bing Search
DuckDuckGo	DuckDuckBot	Collects pages for DuckDuckGo’s private search engine
Yandex	YandexBot	Crawls websites for Russia’s Yandex Search
Baidu	Baiduspider	Discovers content for China’s Baidu Search

If you accidentally block one of these bots in your website’s robots.txt file, that search engine won’t be able to crawl your site. And if it can’t crawl it, your site won’t appear in search results.

The Stages of Search Engine Crawling

Before a search engine can show results, it first has to crawl and process web pages. This isn’t a simple process. It happens in five main stages. Let’s go through each one.

1. Discovery – Finding New Pages

The first step is to find pages that Google hasn’t crawled yet. Search engines like Google use bots (Googlebot) to search for new content.

Think of it like a massive to-do list. Google’s bot is already checking millions of pages in its queue. That’s why you must make your site easy to crawl – you don’t want it stuck at the bottom of the list.

How does Google discover new pages?

• By revisiting old pages to see if they’ve changed.
• By reading an XML sitemap, which lists important pages on a website.
• By following internal and external links from other pages.

Just because Google finds a page, that doesn’t mean it will index it. There are many factors that decide whether a page makes it into Google’s search results.

2. Fetching – Retrieving the Page

Once Google finds a page, it requests access to it from the website’s server.

If everything works fine, the server sends the page’s content back to Googlebot. This usually happens in HTML format, which includes the page’s text, layout, and links. Sometimes, the browser also processes images, stylesheets, or JavaScript files on the page separately.

If the server is slow or unresponsive, Googlebot may struggle to fetch the page properly. In some cases, it may skip the page altogether or delay crawling it.

3. Parsing – Analysing the Content

After Googlebot fetches a page, it doesn’t just store it right away. Instead, it analyses the page to understand what’s on it. This is called parsing.

During this step, the bot extracts important details, such as:

Links – Internal links (within the site) and external links (to other websites). These help bots find even more pages.

Resources – Images, videos, CSS files, and JavaScript that affect how the page looks and works.

Metadata – Title, description, and keywords, which help search engines understand what the page is about.

If there are technical issues, like broken links or missing resources, Google might not process the page correctly.

4. Rendering – Understanding the Page Like a User

Many modern websites use JavaScript to load content dynamically. That’s a problem because search engines can’t always read JavaScript immediately.

To fix this, Google goes through an extra step called rendering. This means the bot loads the page like a real user, executing the JavaScript to see how the full page appears.

This step is important because:

• Some content only appears after JavaScript runs. If Googlebot doesn’t render the page, it might miss important details.
• If JavaScript takes too long to load, Google might give up before it sees the full page.

Sometimes, errors happen during rendering. For example, if a website has a server issue (like an HTTP 500 error), Google may slow down its crawling or avoid the page altogether.

5. Indexing – Storing the Page in Google’s Database

The final step is indexing. Once Googlebot crawls, fetches, and renders the page, it decides whether to store it in its database (called the index).

If Google indexes the page, it saves information about:

• The text and content on the page
• All the links it found
• Metadata, like the title and description
• Other important ranking signals

Once indexed, a page can now appear in search results. But Google does not index all pages. Google might skip pages that:

• Have low-quality content (too little text, duplicated information, or irrelevant content).
• Are blocked by robots.txt or a “noindex” tag.
• Take too long to load or have broken code.

Crawling vs. Indexing: What’s the Difference?

A lot of people think crawling and indexing are the same, but they’re actually two separate steps in how search engines work.

Let’s break it down in simple terms:

Feature	Crawling – Finding Pages	Indexing – Storing & Organising Pages
What it does	Finds new or updated web pages	Stores and organises page information for search engines
How it works	Bots (crawlers) follow links to discover pages	Bots analyse page content and extract key details
Where info comes from	Links, sitemaps, and submitted URLs	Pages that have already been crawled
Main Goal	Collect data from web pages	Create a searchable database for users
Controlled by	Robots.txt file tells bots what they can or can’t crawl	Robots.txt and “noindex” tags decide if a page is stored
Final Result	A list of pages the bot has found	A database of searchable pages users can find in search results

So, crawling always happens first. A search engine bot finds a page. Then, indexing happens next if Google decides the page is worth storing in its database.

Google does not index all crawled pages. It skips some due to poor content, duplicate information, or technical restrictions. That’s why understanding both steps is important when optimising your site for search engines.How Search Engines Find New Pages

It all begins with discovery. This is when search engine bots go looking for new pages to add to their database. They do this in a few different ways:

Crawling Links: Bots follow links from one page to another, uncovering new pages along the way.

Sitemaps: Search engines check a website’s XML sitemap, which is like a roadmap of all its pages.

Manual Submissions: Website owners can speed up discovery by submitting their URLs directly through tools like Google Search Console.

But just because Google discovers a page, it doesn’t automatically store it in its database. That’s where indexing comes in.

How Search Engines Index Pages?

Once they locate a page, search engines analyse and store it so users can find it when searching for similar topics. During this indexing phase, Google looks at different ranking factors, including:

• Content Quality & Relevance: Is the page useful and informative?
• Keywords: Do the words on the page match what people are searching for?
• Title Tags & Meta Descriptions: Have they properly optimized them for search engines?
• Header Tags (H1, H2, etc.): Does the content have proper structure?
• Internal & External Links: Are there links to and from other relevant pages?
• Image Alt Text: Do the images have proper labels for search engines?
• Page Speed: Does the page load quickly?
• Mobile-Friendliness: Does the page work well on mobile devices?
• Structured Data: Is there extra code that helps search engines understand the content?
• Freshness: Is the content up to date?
• Domain Authority & Trustworthiness: Is the website credible?
• User Engagement: Do visitors spend time on the page or leave quickly?
• Robots.txt & Indexing Rules: Are there any restrictions stopping search engines from saving the page?

Not all pages get indexed. If a page has low-quality content, duplicate information, or technical issues, it might not make the cut. That’s why optimising for search engines is important.

Final Thoughts

Search engine optimization can get technical, but understanding how search engines find and store your pages can give you an advantage. Simply put, if Google doesn’t crawl your site, your business won’t be visible online. That’s where SEO by Gordon Digital can help.

To improve your chances of getting indexed:

• Keep your XML sitemap updated so Google knows which pages are most important.
• Use strong internal linking to help crawlers navigate your site easily.
• Follow SEO best practices to ensure your site is properly structured.

The better search engines understand your site, the higher your chances of showing up in search results.