Full-page caching (FPC) is a performance strategy where the complete, final HTML output of a WordPress page is saved to disk or memory after the first request, then served directly to subsequent visitors without re-executing PHP or querying the database. A fully cached page can be delivered in under 50 milliseconds; an uncached WordPress request that triggers database queries and template rendering can take 500ms–2 seconds on a typical shared server. Full-page caching is distinct from object caching (which caches individual database query results) and fragment caching (which caches specific page components). Implementation options include: server-level caching built into managed hosts (WP Engine's EverCache, SiteGround's SuperCacher), caching plugins (WP Super Cache, W3 Total Cache, WP Rocket), or CDN-level HTML caching (Cloudflare APO). Cache invalidation — expiring the cached copy when content is updated — is the core complexity: most implementations auto-purge on post save, but scheduled or dynamic content may require custom purge logic.
Glossary entry