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Topic Clusters: How to Group Keywords and Boost Your SEO

Want to skyrocket to the top of search engine results and bring in qualified traffic? It's not enough to rely on sporadic content. If you want to raise your site's authority and rank well on Google for your top keywords, you need a SEO content strategy that targets the keywords and topics your customers are searching. That's where topic clusters come in.

Topic clusters are the go-to content marketing and SEO Content strategy for marketers - and it's easy to see why. Businesses everywhere are seeing how creating content by focussing on “clusters of keywords” works effectively to increase organic traffic.

So, what are topic clusters and how can you use them to truly nail your SEO and dominate the rankings?

Read on for our guide on building your keyword groups and successfully creating content clusters at scale.

What are topic clusters?

Topic clusters are a way to organise your content to improve your website’s ability to rank for keywords, while also making it easier for human users to navigate.

The main idea of a topic cluster (also referred to as a content cluster) can be broken down into three steps:

  1. Create one long page filled with content on one of your most important target keywords (or phrases).

  2. Then, create several shorter posts or pages targeting long-tail keywords (usually based around questions your target audience is asking).

  3. Connect them all to each other using internal links.

Sounds simple, right?

Let's break down the three elements that make up a topic cluster:

What is a Pillar Page?

Your pillar page is the foundation on which a topic cluster is built.

Let's say you’ve done your keyword research and you have a few thousand keywords that mean roughly the same thing, or have the same intent behind them. You group them together and these are your keyword clusters - a group of keywords that are incredibly similar in theme or topic, and can be targeted together on a single page. 

Your pillar page will usually be a few thousand words in length on a single page. It will broadly cover a specific topic or keyword theme, while leaving room for the cluster content to go into more detail.

When creating a pillar page (or pillar content), you have one goal: to be the most authoritative, high-quality content for a given keyword.

The idea of a pillar page is to be highly linkable, so that external sites link to it as a resource for a content. This boosts your SEO link juice, which is great news for your search ranking.  

What are the Cluster Pages?

The cluster pages, or supporting pages, cover smaller subtopics of the overall topic. These pages can focus on informational long-tail keywords, such as “How to,” “Can I,” etc.

So, while the pillar page covers every aspect of a topic, a supporting page might only answer one question in relation to it.

What are the Hyperlinks?

The internal linking structure between the topic cluster pages is crucial to create an effective topic cluster.

Your cluster pages will link to each other using exact match keywords in hyperlinks, which helps them rank for their target keyword. And each supporting page will link directly back to the pillar page using an exact match keyword in the hyperlink.

This helps distribute your site’s link juice throughout your cluster while also boosting the topical relevancy of your pillar page. So, Google sees lots of topic-related pages linking to each other and creating authority for the website.

Here’s a graphic by HubSpot to explain the relationship between a pillar page and cluster content:

topic cluster graphic

Here's an example:

Let’s say you are a health insurance company that focuses on pet insurance. One of your pillar content pieces could be focused on the keyword “Dog Health”.

Under the umbrella of this long-form piece, you could have topic clusters around keywords like:

  • Most common dog health problems

  • Essential dog health checks and vaccinations

  • How to find the right vet

These pieces would then be hyperlinked back to the pillar page.

 

Why search engine algorithms and content marketers love topic clusters

There are lots of reasons to love topic clusters. When planned and implemented properly, a topic cluster tells search engines that your content is authoritative and relevant - in other words, your content provides in-depth expertise and explanation of a specific topic.

Here's the thing: when you create well-researched content that is useful and relevant to your target audience, you are creating content that people can actually use — and that’s precisely how you earn great rankings on search engines, brilliant traffic AND a winning reputation.

How do we know the topic cluster model really works?

Back in 2016, HubSpot’s Anum Hussain and Cambria Davies launched topic cluster experiments for a select group of topics.

The extensive findings from their initial topic cluster experiments proved that the more interlinking they did, the better the placement in search engine results pages (SERPs). In fact, impressions also increased with the number of links between the topic clusters.

Now let’s take a look at the reasons why you should consider topic clusters for your content digital strategy:

1. They make it easy for search engines to index and rank you

Topic clusters make it easy for search engines to crawl your site. By organising your content into topic clusters and using internal linking, search engine bots can make sense of your content, index it and rank it.

Without topic clusters, you are simply building more and more pages that don't have any linking structure. As content grows, blog posts proliferate and the structure becomes more complex, which makes it difficult for search bots to crawl through the pages quickly and index them.

You'll also wind up with tons of web pages that cover similar keywords and topic areas. These pages compete with each other to get found by search engines and searchers.

However, with a topic cluster approach, you benefit from a more organised and well-considered structure that makes it overtly clear to search engines and users what your site is all about and the value it offers.

2. You earn more topical relevance

Google’s mission is to deliver “useful and relevant results in a fraction of a second.”

What are these “useful and relevant results” that Google is talking about? 

Content.

The more useful and relevant your content is to your audience’s search query, the higher your site will rank.

Simple as that.

When you create topic clusters, you are keeping your content, such as blog posts, guides and pages, focused on one theme that you know your users are searching for. This helps you provide hyper-relevant content, which Google will reward.

3. They give your users a better experience

It's not all about the search bots - humans also want to see that your content is relevant to what they are looking for. They want to know you are an authority on a particular topic, and that they can trust you for reliable information.

Topic clusters allow you to predictively build content around a core topic that solves multiple pain points for several different buyer personas at various stages of the funnel — without cannibalizing your own keywords.

As a result, you’ll be able to anticipate your users’ follow up questions and provide the right content at precisely the right moment. This keeps users engaged with your content rather than sending them back to Google for answers.

If people know that they can come to you for all the best, detailed information on a particular topic, you are making their life easier. They don't have to keep browsing thousands of search results to find the answers to their questions - it's all right there on your site.

Best of all, the information they need is just a click or two from the pillar page. The way you create topic clusters with internal linking means they don't have to search through your whole site.

Now that's what we call a great user experience!

4. Topic clusters make you plan ahead

It's easy to think that SEO and content marketing is just about writing a few blog posts focused on a keyword. But that's not enough.

The topic cluster method forces you to plan ahead and really think about how your content is answering what your audience wants. When you take a topic cluster approach to keyword research, you naturally begin to group keywords and phrases into buckets. So, you can work with an organized list of keywords grouped by blog post, topic cluster, and blog category - rather than a scattergun approach.

The best part is that topic clusters can actually help make the whole process easier for content marketers and content strategists.

Once you find a topic that your audience is searching for, the hard work is done! All you need to do now is separate it into clusters and create the pages.

5. They attract repeat visitors

Content marketing helps grow your audience and build a loyal following, which hopefully turns into paying customers.

If you use topic clusters, you are giving people a reason to come back to your site over and over again. After all, you are creating high-quality content on topics relevant to your audience.

That’s the power of clustering your content. 

 

Examples of brands that leverage topic clusters well

Need some inspiration to create your first pillar page and start building strong internal links and authority? These two brands are leveraging content clusters for maximum rewards.

Example 1: HubSpot

You can't talk about content clusters without talking about HubSpot. They're not only masters of topic clustering, their cofounder Brian Halligan coined the term himself in 2005. 

HubSpot’s How to do Market Research is one example of their content clusters at work.

 

Hubspot pillar page example

 

The pillar page is a whopping 23 minutes of reading and filled with related content, such as templates, free tools and other blog posts. It also includes a table of contents, which HubSpot includes on all its pillar pages.

Pillar page table of content

Example 2: Xero

This leading bookkeeping software company aims to provide small businesses and sole traders with helpful resources to make running their business a breeze. And what's the one thing business owners dread? End of financial year.

That's why we love this End of Financial Year Tax and Accounting content cluster.

What's so great about this pillar page?

It breaks down the content in a structured way, with lots of related content for users to explore, such as Setting Up for New Year and Processing Payroll.

pillar page example - xero

There's also a long FAQ section - which is a great way to build out content and climb search rankings.

long FAQ section example

 

3 Common mistakes you can make with topic clusters

1. You leave the pillar page to stagnate

There's nothing that will send website visitors away faster than stagnant, out of date content. So, once you create pillar content, don’t just let it sit there and age.

As frequently as you can, add fresh statistics, tips, examples, and quotes to make sure your content stays relevant. These elements will help it keep it high in search rankings.

2. You create link silos

A link silo is where you don’t link between different topic clusters in order to deliberately concentrate relevance.

However, there's a problem with this strategy: it fails to capture the rewards of internal linking opportunities that pass along PageRank and context between related content.

Remember - everything is connected, and creating links between related content helps Google understand the relationships between different clusters and return the best results for users.

3. Content flooding

It's easy to get carried away with topics and create heaps of blog posts that target very similar keywords. But there can be too much of a good thing!

If you create ten posts that all target the same general keyword, the pages will compete with each other for rankings. This is known as cannibalization.

But you can avoid it. Simply build cluster pages around unique search terms that address a range of  search intents.

 

How to build topic clusters at scale for more organic traffic 

By now, you should have a solid understanding of why organizing your content into topic clusters is a  rewarding strategy for your SEO marketing.  

The question you want to know is this:

How do you go about grouping pages and keywords together into topic clusters?

Follow these steps:

1. Leverage tools for keyword research and grouping

At the core of the topic cluster model is keyword research.

But not just any keyword research - you need to understand the relationships between the main topic, subtopics, and long-tail keywords.

Doing this manually is a nightmare. It's massively time-consuming.

The good news is there are different tools you can use for this - here are three of our favourites:

Surfer's Content Planner

Most keyword tools aren’t designed to help you with topic clustering, which means you could wind up with thousands of keywords to work with. But Surfer’s Content Planner makes quick work of topic clusters.

Start by entering a broad keyword. Content Planner will analyze Google for the broad search query you want to target.

In this example, Content Planner found and organized 113 keyword clusters on the topic of UX design using live Google data and Surfer’s natural language processing (NLP) algorithm.

SEMrush content planner

The tool also lets you track the performance of the clusters:

surfer content cluster

What you get is a small number of relevant target keywords for each cluster plus the predicted monthly search volume and projected total traffic.

Next, you can plan the internal linking between your clusters - this is essential to the success of your topic clusters.

Content Distribution's Keyword Grouping Tool

The great thing about ClusterAi is that it works with the SEO tool you are probably already using, including Ahrefs, SEMRush, Moz and Google Search Console.

You can import up to 25,000 keywords into ClusterAi, which then matches every keyword against every other keyword and compares the number of pages that rank for both sets of keywords.

When ClusterAi finds three or more pages that rank for a set of keywords, the idea is that you can also rank for this set of keywords with one page also.

At the end, you receive an email with a link to your completed keyword research which you can use to create your content clusters.

KeywordInsights AI

KeywordInsights uses NLP and search engine result page data to cluster keywords into similar groups while also working out the intent behind them. It groups your keywords into important clusters in a way that makes it easy to quickly understand when you need to split content out into new pages or when it can be consolidated.

The tool provides a report which clearly shows you the main keyword each page should target, as well as all the other keywords that page can target.

Best of all, when combined with URL data, the report allows you to work out which clusters can be internally linked.

Why search volume should be evaluated at a topical level 

When it comes to finding the best topics to focus on, keyword difficulty and search volume matter.

A good rule of thumb for the topic cluster model is:

  • Use a broad keyword of hard/medium difficulty but high search volume for a pillar page

  • Sort subtopics by low search volume keywords, including questions and long-tail ones (aka low-hanging fruit keywords)

Again, you can use your preferred SEO tool here to research search volumes, such as Ahrefs,  Moz, HubSpot, LSIgraph, or SEMrush.

Enter your topic, sort results, and choose targeted sub-topics to link together.

Once you gain rankings for these particular search terms, Google sees your website as a trustworthy, authoritative source of information on the topic. Therefore, it is likely to rank you higher for related keywords with higher search volumes.

2. Do keyword research around topics and search intent

How do you work out which content ideas to use for your topic cluster model?

Start by working out your pillar topic, which is the main topic around which you’ll build content clusters.

Don’t be tempted to pick these topics based on guesswork, and don't get caught up on keyword volume.

Think about the buyer's journey here. What are the problems potential customers may want to solve and how do they search for solutions?

How do their questions change as they progress through the funnel?

What actions are they likely to take at each stage?

This goes for B2B content marketing research too.

Remember, search intent changes according to different stages of the buyer's journey:

  • Top-of-funnel (ToFu) queries are more general and informational.

  • Middle-of-funnel (MoFu) searches become more comparative and detailed

  • Bottom-of-funnel (BoFu) searches tend to be specific to brands, products, services and reviews.

Once you have a list, you need to expand on this to create a bigger list of cluster content ideas for your pillar page.

That's where you need to look to Google.

Ask Google to recommend topics that could form your cluster pages.

Simply add a prefix (such as why, how, or when) to the topic in a Google search and see what auto-populated suggestions it throws back at you.

This is where you can see sub-topics that searchers are likely to look for:

subtopics google

 

Then, go to LSI Graph and check that you’re not missing any glaring opportunities to create content.

LSI Graph

After you identify your priority keywords, organize them into buckets. This is where the content cluster tools come in.

If you don't want to use a tool, the best way is to search each term in Google and map it to a head term. This helps you bundle long-tail keywords around a single parent term that represents your cluster page. Then, each cluster page can be mapped to a single pillar post.

3. How to approach internal links between your core topic and different web pages

We've already said it, but it bears repeating: interlinking is everything for the success of your topic clusters.

Your internal linking structure helps search engines understand the relationship between your pages, and therefore their value and relevance.

HubSpot has proven that more internal links led to a higher placement on the search engine results page.

So, how do you approach internal links?

As a rule, for topic clusters, keep the majority of your internal links under the same pillar content. In other words, try not to link out to other blog posts that are related to that topic cluster.

For example, if you tackled the topic "what is content marketing", here’s what the topic cluster would look like:

pillar and topic cluster example - content marketing

Source: Content Marketing Institute

Together, the links provide the search crawlers with an easy way to find, crawl, and index your topic clusters. How to tackle a broad topic using long-form cluster pages and how to think about content creation

Now you've got your topics and understand how they link together, you need to get down to the business of creating the content.

Here's where we're going to tell you to go against your intuition AND write your cluster pages before your pillar page.

Why should you write the pillar page after the topic clusters?

Surely it would make more sense to write the pillar topic first, then going all the specifics, right?

Actually, the opposite is true.

If you write your pillar page first, you run the risk of duplicating content, going into detail that the subtopic clusters will cover and therefore cannibalizing the search rankings of each cluster page.

So, fight the urge!

Writing cluster pages is similar to creating a typical blog post. Use engaging headers and subheads, original data and visual content, and of course, use the best search engine optimisation tactics.

Just remember not to mention anything in detail that will be covered on another cluster page.

Once you've written your cluster content, go back to the pillar topic.

This page is an overview of the topic, without exhausting any subtopic, and should be long-form (at least 3,000 words).

The key here is to keep your pillar content broad.

Touch on the subtopics, but don’t cover them thoroughly. Use calls to action to push readers to your cluster pages so they can learn more.

 

Keep your content marketing machine running

The topic cluster model is a high-reward way to organize your content. It’s an SEO strategy that helps both users and search engines to easily navigate your site’s content and will bring users back over and over again.

Choose a topic that will draw in your target audience. Then, craft your subtopic cluster content and create your pillar page. Finally, add internal links to connect all the pages.

The more you do this, the easier the process will become. It might take a while to get a topic cluster recognised at the top of Google search results for your chosen terms. But like all inbound marketing strategies, the best results come with hard work and time.

Not sure how your existing content is tracking on search rankings? Want to improve your online visibility using an SEO content strategy?

We're here to help. Claim your free SEO audit to see an in-depth report on your current online performance, including content, SEO, PPC and social media. You'll also get a 6-month multichannel game plan to ramp up your performance, results and revenue. It's completely FREE with no obligation.

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