A Beginners Guide To Crawling and Indexing. What’s the Difference and How It Works

Mar 28, 2024
Wooden library index drawers

When you first start exploring the world of SEO, and you’re working hard to get your website showing up on the first page of Google, the strange terminology you come up against can sound strange, and like there’s a whole new language to learn!  

But I want to demystify the most important terms for you so you can confidently get on with optimising your website without worrying about what things mean. Today, I’m going to talk about two foundational terms or processes: crawling and indexing.

Prefer a video? Watch here!

What Is Crawling?

I like to think of search engine crawlers (or spiders or bots) as worker ants or bees sent out by search engines to browse the internet and bring back any new or updated website pages.

Or maybe it’s better to think of them as cartographers, mapping out the ever-expanding internet and laying down the land.

Whatever you want, think of them as a search engine crawler's job is to systematically browse the web to discover and revisit web pages and map out the structure of the internet.

How Does Crawling Work?

Crawlers keep a list of URLs on your website that’s generated from their last visit and refined by your sitemap. 

As the crawlers visit your site, they use the links on your pages to discover new pages and add them to the list of pages to crawl. Crawling is a continuous cycle of discovery and rediscovery, allowing search engines to keep up with the ever-changing and growing internet.

To make sure your website is easily crawlable, you need to have a well well-structured website with clear navigation and quality internal links so crawlers can easily discover and understand your content.

What is Indexing

Once a crawler visits a website, the next step is indexing. 

Indexing is the process of analysing and storing web pages in a vast database known as an index. 

When someone does a search, a search engine like Google goes to their index to provide the most relevant results. 

It’s a bit like a huge library catalogue system where each book or website page is categorised, shelved and indexed so it can be easily found.

How Does Indexing Work?

Once the crawlers bring back their updated information and drop it off at the huge data centres, the indexing process begins. 

During indexing, search engines carefully assess the page’s content and structure and work to understand the page’s topics, images, videos, and the user experience it offers. 

The more comprehensive and relevant a page's content is, the better its chances are of being indexed and ranked high in search results.

Not every page is indexed by the search engines. To be deemed worthy of being indexed, and having a chance to show up in the SERPs, your page needs to pass the indexing assessment, i.e. be relevant, of suitable quality, deliver value and be properly structured. 

What’s The Difference Between Crawling and Indexing

While crawling and indexing are closely linked, they are two distinct processes:

Crawling is the discovery phase, where search engines send out bots to find new and updated web pages.

Indexing is the analysis and storage phase, where the content of these pages is evaluated and added to the search engine's index for future retrieval.

A web page must first be crawled before it can be indexed. However, not all crawled pages are indexed. 

Search engines use algorithms to decide which pages are valuable enough to be stored in their index.

So What Does This Mean For Your SEO?

It means you need to make sure your pages are crawlable and of a standard that will pass muster with the Indexing process.

If you make sure your pages are crawlable and index-worthy, you’ll have taken great steps to having an optimised website, and you’re much more likely to show up on Page One of the search results. 

Here are some steps you can take to ensure just that:

  • Make sure your website is crawlable by using a clean structure, meaningful URLs, and a robots.txt file that accurately guides search engine bots.
  • Try and get your content to be indexable by focusing on quality, relevance, and keyword optimisation. 
  • Use meta tags, including title and description, to improve your chances of being indexed.
  • Use sitemaps to tell search engines about the organisation of your site content. This will help both the crawling and indexing processes.
  • Monitor and improve site performance and user experience, as these are considered during indexing.
  • Regularly update your content to encourage frequent crawling and reflect the dynamism of your site.
  • Optimise your site's load time and mobile responsiveness, as these factors impact both crawling efficiency and indexing quality. 

So, That’s Crawling and Indexing.

I hope you’ll see how important crawling and indexing are for getting your to show up in the search results now.

If your site isn’t set up properly so it can be crawled easily, the bots won’t have anything to take to the search engine HQ to index. And if there’s nothing to index, there’s nothing to show in the search results.

Even if your pages are being crawled and taken back to the data centres for indexing, you need to make sure your pages are index-worthy, or they still won’t show up in the search engines!

Crawling and Indexing are fundamentally important to getting your website to show up in the search engines, so make sure you look at those action steps and see what you need to do.

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