The INI file format is an informal standard for configuration files for some platforms or software. INI files are simple text files with a basic structure composed of sections, properties, and values.

In MS-DOS and 16-bit Windows platforms up through Windows ME, the INI file served as the primary mechanism to configure operating system and installed applications features, such as device drivers, fonts, startup launchers, and things that needed to be initialized in booting Windows. INI files were also generally used by applications to store their individual settings.