How Cache works in Drupal

Caching process is done with the help of cache.inc file

cache_clear_all [ cache_clear_all($cid = NULL, $table = NULL, $wildcard = FALSE) ] Expire data from the cache. If called without arguments, expirable entries will be cleared from the cache_page and cache_block tables. cache_get [cache_get($key, $table = 'cache') ] Return data from the persistent cache. Data may be stored as either plain text or as serialized data. cache_get will automatically return unserialized objects and arrays. cache_set [cache_set] Store data in the persistent cache.