A topic cluster is a group of related content pieces built around one main “pillar” topic. The pillar covers the topic broadly, while cluster pieces cover specific subtopics — all linking back to the pillar.
8–15 cluster pieces per pillar is ideal. This signals to search engines that you have deep expertise on the topic, which improves rankings for all pieces in the cluster.
Typically 3–6 months for SEO results. For YouTube, the algorithm can pick up on topical authority faster — sometimes within 4–8 weeks of consistent uploads on the same topic.