Config.xml is a global configuration file that controls the build settings of the Ionic apps. It controls many aspects of a Cordova application behavior. When you scaffold the Ionic application, a basic config.xml file is generated for you in the top-level directory. This file follows the W3C Package Web Apps (widget) specification. It allows developers to specify metadata about their applications easily. It contains various information about the project, such as package name, version, author's information, plugins, platform, etc.