Algorithm
Topical authority
The perceived depth and breadth of a domain's coverage of a topic. Post-HCU, depth + first-hand expertise are weighted more heavily than breadth.
What it is
The perceived depth and breadth of a domain's coverage of a subject, reflecting how thoroughly and credibly it addresses a topic and its subtopics. Since the helpful content shift, depth combined with first-hand expertise is weighted more heavily than sheer breadth.
Why it matters
Strong topical authority lifts rankings across a whole subject cluster and makes a domain a likelier source for AI-generated answers. It compounds, so authority earned on core subtopics raises the visibility of related pages.
How it works
It is built by covering a topic and its meaningful subtopics with genuine expertise, internal linking, and consistent intent fit, so the response is to map subtopics and fill gaps with substantive, experience-led content. Avoid padding the cluster with thin pages, which now dilutes rather than strengthens authority.
When it applies
It applies whenever a domain competes within a defined subject area or content cluster.
Examples
- A site that ranks for a head term and most of its supporting questions and subtopics.
- A specialist blog outranking a larger generalist site within its niche.
- A cluster gaining strength after deep guides replace a scatter of thin posts.
How it is measured
- Share of subtopic queries within a cluster where the domain ranks
- Internal link density and coherence across the cluster
- Proportion of the cluster's pages showing first-hand expertise
- Citation share within the topic on AI answer surfaces
Related terms in Algorithm
- Core updateA broad Google algorithm update affecting search rankings sitewide rather than a single feature. Recent core updates (e.g. May 2026) have increasingly favoured intent-aligned content over keyword-optimised content.
- EEATGoogle's quality framework: Experience, Expertise, Authoritativeness, Trustworthiness. EEAT signals are increasingly weighted in both classical ranking and AI Overview source selection.
- Helpful Content UpdateGoogle's quality-focused update class targeting low-value, AI-generated, or thin content. Successive HCUs have favoured first-hand experience and named expertise over comprehensive but shallow coverage.
- SERP volatilityThe rate of change in search result rankings over a time window. High volatility usually signals a core update or major spam action in progress.