What it is
Topical authority is what you have when your site is clearly an expert on a subject, not just the owner of one decent page about it. It comes from covering the whole topic: the main questions, the edge cases, the related concepts, all connected and kept current. Depth and coherence, not a single viral post.
Why it matters
Answer engines have to decide which sources to trust, and breadth of credible coverage is a strong tiebreaker. A site that thoroughly owns a topic is more likely to be pulled for the many sub-questions a fanned-out AI query generates. This is how you move from getting cited occasionally to becoming a default source in your space.
What to do
Pick the topics you genuinely want to own and map the full set of questions around each. Build hub pages that link to detailed sub-pages, fill the gaps competitors skip, and keep the cluster updated so it reads as living expertise.