API Application programming interface. The published methods for using a set of programs. In Joomla, the API refers to the public methods and fields of all the defined classes, especially ones in the Joomla platform. Because third-party programs rely on the API, it should be changed as infrequently as possible and always with advanced notice.
Language Languages are perhaps the most basic and critical extension type. Languages are packaged as either a core language pack or an extension language pack. These packages consist of INI files which contain key/value pairs. These key/value pairs provide the translation of static text strings within Joomla! source code. This allows both the Joomla! core and third party components and modules to be internationalised. Core language packs also include an XML meta file describing the language and providing information about the fonts to use for PDF content generation. Reference: http://docs.joomla.org/Glossary
