Introduction to Using Drupal Cache

For anyone that stumbles on my site, I thought I would share this helpful article from Lullabot on A beginner's guide to caching data in Drupal 7.  I found it both interesting and useful.  I hope that it will be enlightening to you as well.

Building complicated, dynamic content in Drupal is easy, but it can come at a price. A lot of the stuff that makes a site engaging can spell 'performance nightmare' under heavy load, thrashing the database to perform complex queries and expensive calculations every time a user looks at a node or loads a particular page.
...because page level caching is an all-or-nothing affair, it only works for the standardized, always-the-same view that anonymous users see when they arrive.
Eventually there comes a time when you have to dig in to your code, identify the database access hot spots, and add caching yourself. Fortunately, Drupal's built-in caching APIs and some simple guidelines can make that task easy.