Cache has been used for the site or system to improve the content delivery fast for the end-users. This topic is created to explore about Drupal inbuilt caching mechanism and provide info how to use it. We need to explore Drupal's inbuilt caching feature with the external contributed modules like Varnish, Memcache, Authcache, File cache etc. those are available to improve the site performance. You can found the best suited example and caching options to use with your site in this topic.