Page caching is a performance technique where the fully rendered HTML output of a WordPress page is saved to disk or memory after the first request, then served directly to all subsequent visitors without re-executing PHP or running database queries. Without page caching, every request triggers PHP execution, multiple database queries, and template rendering — a process that can take 500ms to 2 seconds on a busy shared server. With a page cache in place, the pre-built HTML file is delivered in under 50 milliseconds. Page caching is distinct from object caching (which caches individual database query results in memory) and fragment caching (which caches portions of a page). Most managed WordPress hosts implement page caching at the server or CDN level — WP Engine calls theirs EverCache. Plugin-based solutions (WP Super Cache, W3 Total Cache, WP Rocket) work on any host. Cache invalidation logic — automatically purging the cached copy when content changes — is the most nuanced part of implementation.
Glossary entry
