In more detail
The idea is simple. A site that covers a subject thoroughly, with clear and accurate pages on its main questions and subtopics, written by people who know the area, is more likely to be seen as a reliable source on that subject than a site with a single page on it.
In practice, building topical authority usually involves:
- Mapping the topic: the core subject, the questions people ask and the subtopics, informed by keyword research and real customer questions
- Hub and cluster pages: a broad guide on the main subject linking to detailed pages on each subtopic, and back again, using clear internal links
- Depth and accuracy: content that answers questions fully, with first-hand experience and evidence, in line with E-E-A-T
- Maintenance: updating pages as the subject changes, and merging overlapping ones
Google doesn't publish a "topical authority" score. Its guidance on helpful, people-first content does ask whether content demonstrates first-hand expertise and depth of knowledge, and warns against producing lots of content on many topics in the hope that some of it will rank. Focus is part of the point.
Why it matters when hiring an agency
Topical authority explains why content plans should be organised around subjects that matter to your business, not around isolated keywords. Ask agencies how they'd structure your content into topics, how new pages will connect to existing ones, and how your in-house experts will be involved.
Be cautious of plans that publish large volumes of loosely related articles. Breadth without depth or expertise is the "search engine-first" pattern Google describes, and it rarely builds trust with readers or search engines.