INI file

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.

In Windows NT Microsoft introduced the registry, and began to steer developers away from using INI files for configuration. All subsequent versions of Windows have used the Windows Registry for system configuration, and applications built on the .NET Framework use special XML .config files. The APIs still exist in Windows, however, and developers may still use them.

The name "INI file" comes from the commonly used filename extension .INI, which stands for "initialization". Other common initialization file extensions are .CFG, .conf, and .TXT, especially 'config.txt' occurrences.

Linux and Unix systems also use a similar file format for system configuration. In addition, platform-agnostic software may use this file format for configuration. It is human-readable and simple to parse, so it is a usable format for configuration files that do not require much greater complexity.

The basic element contained in an INI file is the key or property. Every key has a name and a value, delimited by an equals sign (=). The name appears to the left of the equals sign.

Keys may (but need not) be grouped into arbitrarily named sections. The section name appears on a line by itself, in square brackets ([ and ]). All keys after the section declaration are associated with that section. There is no explicit "end of section" delimiter; sections end at the next section declaration, or the end of the file. Sections may not be nested.

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