The document discusses the history and versions of the content management system Joomla. It describes the major releases including Joomla 1.0, 1.5, 1.6/1.7, and the current version 2.5. The key components and considerations for upgrading Joomla sites are also outlined, such as verifying compatibility of components, modules, plugins and templates, and whether an upgrade will require a new installation or is a simple process. Tips are provided on finding appropriate third party tools on the Joomla website.