.ini File — Initialization File

INI (Initialization) files are one of the oldest and simplest configuration file formats, using a plain text structure with sections (in square brackets), keys, and values. The format originated in early versions of Microsoft Windows for system and application configuration (win.ini, system.ini) and has remained popular due to its extreme simplicity. INI files use [Section] headers to group related settings, with key=value pairs below each section. The format supports comments (typically prefixed with ; or #) and is trivially parseable with minimal code. While INI lacks the hierarchical nesting, data types, and standardization of modern formats like TOML, YAML, or JSON, its simplicity makes it appropriate for simple configuration needs. INI files are used by PHP (php.ini), MySQL (my.cnf/my.ini), Git (.gitconfig), Python (setup.cfg), many Windows applications, and the systemd unit file format. The format's main limitation is the lack of a formal specification — different implementations handle edge cases like multi-line values, duplicate keys, and escape sequences inconsistently. Despite these limitations, INI remains widely used for simple key-value configuration.