As a site grows, the overhead of executing so many queries per page against the database starts to add up. This is where caching can benefit a high traffic site. Drupal core caching Caching stores "elements" in a cache table in the database, so the data can be retrieved by a single query, rather that constructing the page from individual elements. Drupal's core cache has two parts, stuff that gets caches no matter what, and stuff that is optional via an administrator defined settings.

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