Topic cluster
What is a topic cluster?
A topic cluster is a group of interlinked pages that together cover one subject. A central pillar page gives a broad overview of the topic and links out to cluster pages, each of which covers one subtopic in depth and links back to the pillar. It is also called a hub-and-spoke model.
For example, a pillar page on “home composting” might link to cluster pages on composting in a flat, what not to compost, hot versus cold composting, fixing a smelly compost bin and choosing a compost bin. Each cluster page targets its own keyword and search intent; the pillar targets the broad head term.
Clusters are usually built from keyword research. You group related keywords by the page that should answer them (keyword clustering), decide which group is the broad overview and which are subtopics, and map each group to one URL. That map also prevents keyword cannibalisation, where several of your pages compete for the same query.
The internal links are what make it a cluster rather than a pile of related articles. They help readers move between related pages, help search engines discover and understand the relationship between pages, and pass link value from pages that earn links to those that need it.
Why topic cluster matters for SEO
Search engines and AI systems reward sites that cover a subject thoroughly. A cluster shows breadth (many subtopics) and depth (each one properly answered), which builds topical authority and makes each page in the cluster more likely to rank than an isolated article would be.
Clusters also match how AI search retrieves information. Systems that use query fan-out search for many subtopics of a question; a site with a good page for each subtopic has more chances to be retrieved and cited.
They make planning easier, too. A cluster turns a vague goal (“write about composting”) into a defined list of pages, shows which are missing, and gives each new article an obvious place in the site’s structure.
How to build a topic cluster
- Choose a core topic that matters to your business and is broad enough to have many subtopics.
- Research keywords around it: start with a seed term and collect matching terms, questions and related searches.
- Group the keywords by intent. Keywords that return mostly the same top results usually belong on one page.
- Pick the broadest group as the pillar and the rest as cluster pages. Write down which URL targets which keyword group.
- Check what you already have. Map existing pages to the plan, merge duplicates and note the gaps.
- Write or improve the pages, starting with those that have the best mix of demand, business value and realistic difficulty.
- Link every cluster page to the pillar and the pillar to every cluster page, with descriptive anchor text. Link between cluster pages where it helps the reader.
- Track rankings for the whole cluster and add pages as you find new subtopics.
Topic cluster example
Pillar: “Home composting: a beginner’s guide” (/composting). Cluster pages: /composting/in-a-flat, /composting/what-not-to-compost, /composting/hot-vs-cold, /composting/smelly-compost-bin, /composting/best-compost-bins. Each links to the pillar in its introduction; the pillar has a short section and a link for each.
Topic cluster FAQ
How many pages should a topic cluster have?
There is no fixed number. Cover the subtopics people actually search for and that your audience needs; for most topics that is somewhere between a handful and a few dozen pages.
Do topic clusters still work for SEO?
Yes. Organising content by topic with strong internal linking helps search engines understand your site and helps readers find related pages. The label matters less than the coverage and the links.
What is the difference between a topic cluster and keyword clustering?
Keyword clustering groups keywords that one page can rank for. A topic cluster is the set of pages built from those groups, linked around a pillar page.
Should cluster pages be in a subfolder?
It can help people and tidy reporting, but it isn’t required. The internal links between the pages matter more than the URL structure.
How do I choose a pillar topic?
Pick a subject that is central to what you sell, broad enough to have many subtopics people search for, and narrow enough that you can cover it well. If you can’t list at least five useful subtopics, it is probably a cluster page, not a pillar.
Related SEO terms
A pillar page is a broad, in-depth page on a core topic that links to more detailed pages on each subtopic, forming the hub of a topic cluster.
Topical authority is a site’s perceived depth and expertise on a subject, built by covering it thoroughly and being cited on it.
Keyword clustering is grouping keywords that share intent and search results, so each group can be targeted by one page.
Internal links are links from one page on your site to another. They help visitors navigate, help crawlers find pages and spread link authority.
Keyword mapping is assigning target keywords to specific pages on your site, so every page has a clear focus and no two pages compete.
Site architecture is how a website’s pages are organised and linked together, which shapes how people and search engines find and value them.