A configuration file, also known as config file, is a file that stores data used to configure a software system such as an application, a server or an operating system.
Some applications provide a tool to create, modify, and verify the syntax of their configuration files – sometimes via graphical user interface (GUI). For context, system administrators may be expected to create and modify text config files via a text editor. For server processes and operating-system settings, there is often no standard tool, but operating systems may provide graphical interfaces such as YaST or debconf.