Through caching Drupal allows to speed up website using different configuration like page caching, block caching and lifetime for cached pages.
Page Caching: It enables the entire HTML of each page to be stored in the database. It reduces the amount of queries needed
Block Caching: You can set the cache setting for a block in views, when block created by views
Minimum cache lifetime: It is the amount of time before the page cache is cleared. On each cron run, page caches are cleared.
Expiration of cached pages: It only applies for an external mechanism, for example, your browser cache or varnish
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