Out-of-the-box, Drupal stores its own "cache" of site content, blocks, menus, templates and stylesheets.  (This is separate from any server level caching that may be in place such as Varnish or Memcache). 

As a result, should any content changes, menu changes, block changes, as well as recently deployed code changes not be reflected immediately, you may want to try clearing the Drupal cache before clearing your own browser history/testing in a private/incognito browser window.

Site Managers and Administrators have the ability to flush Drupal's "cache" via the Administration Menu.  Hover the Home icon and either "Flush all caches" or selectively flush the cache for just a particular subset of items.