TSconfig Reference
TSconfig Reference covers both Page TSconfig and User TSconfig, with which you are able to change the behavior of the backend in parts. You can change labels, hide or show fields, set permissions and default values. This reference explains which options are available in TYPO3 CMS.
TypoScript Reference
The TypoScript Reference describes the different functions and objects which can be used to configure the frontend output, including the full page template and the rendering of individual content elements according to their type.
Fluid ViewHelper Reference
The Fluid ViewHelper Documentation is useful when you work with the Fluid templating engine.
TCA Reference
The TCA Reference is only relevant for developers. It describes the global array called $GLOBALS[‘TCA’]. This array is a layer on top of the database tables that TYPO3 can operate on. It is a very central element of the TYPO3 architecture.