What it means
Instead of one page chasing one keyword, you build an interlinked cluster — a pillar page plus supporting articles — that covers a topic thoroughly. Over time, the engine learns your site is a definitive source on it.
Why it matters
A single great article rarely outranks an entire authoritative cluster. Topical authority is how smaller sites beat bigger ones in a niche: pick a subject you can genuinely own, cover it end to end, and interlink it well. It compounds — and it is exactly what AI engines look for when deciding whom to cite.