What is a content cluster?

A content cluster is a group of interlinked articles organized around a central topic. It consists of one pillar page (comprehensive overview) and 10-20 cluster pages (subtopic deep-dives) that all link to each other and back to the pillar.

Example cluster for "International SEO": Pillar page: "The Complete Guide to International SEO" (3,000+ words covering everything). Cluster pages: "How Hreflang Tags Work", "Subfolders vs Subdomains for SEO", "Content Localization Best Practices", "International Keyword Research", "Multi-Region Link Building". Each cluster page links to the pillar and to 2-3 other cluster pages.

Why clusters work: they signal topical authority to Google. A site with 15 interlinked articles about international SEO demonstrates deeper expertise than a site with one article. Google rewards comprehensiveness — the site that covers a topic most thoroughly tends to rank highest across all related keywords.

How to build: 1) Choose a topic your business should own. 2) Write the pillar page covering the topic broadly. 3) Identify subtopics with search volume. 4) Write cluster pages for each subtopic. 5) Link everything together — pillar links to all clusters, clusters link to pillar and to each other. 6) Update the pillar page quarterly.

The Empirium blog uses exactly this structure — 5 pillars, 20 articles each, all interlinked.