Google's systems increasingly reward sites that demonstrate broad topical coverage alongside genuine, demonstrable expertise. The two are related but not identical, and confusing them leads to weak content strategy.
Topical authority
This is coverage depth — do you have content answering every reasonable question a user might have within a subject cluster, linked together in a clear hierarchy?
Expertise
This is about who is saying it — author credentials, first-hand experience, and original data or opinion that could not be copied from a competitor.
The sites winning in 2026 build both: a well-structured topic cluster, written or reviewed by people who can prove they know the subject.