Configuration.php is the main Joomla configuration file in the site root. It contains database connection details and a range of global CMS settings.
What the file contains
Typical values include database settings, the table prefix, log and temporary paths, mail options and the offline state. Joomla updates the relevant values when global configuration is saved. Parameters belonging to individual components, modules and plugins are usually stored in the database.
Working with configuration
Prefer the Global Configuration interface. Before editing the file manually, keep a backup and check PHP syntax. Incorrect database credentials or paths can make Joomla unavailable. The file contains sensitive values, so never publish it or leave accessible backup copies alongside it.
Configuration.php describes the site environment. It does not replace a backup of the Joomla database and files.