Topic Cluster
In one line
A topic cluster is a content structure where one hub (pillar) page sits at the centre and a set of narrower sub-topic pages link back into it.
Going deeper
A topic cluster pairs one hub page on a broad theme A with a set of cluster pages that go deep on its sub-topics — a1, a2, a3 — all tied together by internal links. HubSpot popularised the model, and it's effectively the default way SEO content gets architected today.
Before building the structure, teams usually run keyword clustering: group semantically related queries into chunks small enough for one page to fully resolve. Those groups become the skeleton of each cluster page. Cram too many keywords into a single cluster and you slide into cannibalization, so the craft is in deciding what splits and what merges.
Topic clusters carry over cleanly into AI search. LLMs answering category-level questions tend to favour sites that map a topic systematically, so a well-built cluster doesn't just rank — it earns citations across many related prompts.
Related terms
Pillar Page
A pillar page is the hub at the centre of a topic cluster — a broad page on a large theme that interlinks with the narrower cluster pages around it.
SEOCornerstone Content
Cornerstone content is the small set of pages your site relies on most for traffic, conversions and citations — the load-bearing columns of the content house.
SEOKeyword Clustering
Keyword clustering is the practice of grouping keywords with the same intent so they map onto a single page or topic cluster — used to prevent cannibalization and to build topical authority.
SEOInternal Linking
Internal linking is the practice of connecting pages within the same domain — and it shapes crawl efficiency, how authority flows between pages, and how users move through the site.
SEOTopical Authority
Topical authority is the credit a domain earns when search engines decide it covers an entire subject area deeply and consistently — not just one or two posts.