Dynamic Page Cache is a core module that caches parts of a page while leaving personalised sections uncached. Unlike the internal page cache, it works for authenticated users as well as anonymous ones.
It caches the cacheable portions of a page, like the main content, and fills in dynamic parts like personalised greetings on each request. This is achieved through Drupal’s cache metadata system, which tracks exactly what can and cannot be cached.
Dynamic Page Cache is enabled by default and works transparently with modules that implement the cache API properly. When BigPipe is also enabled, the uncached sections are streamed after the cached shell, giving the best of both worlds. For authenticated heavy sites, dynamic page cache is essential. Without it, every page request rebuilds the entire page from scratch, which is slow and wasteful.