The INI file format is a de facto standard for configuration files. INI files are simple text files with a basic structure. They are commonly associated with Microsoft Windows, but are also used on other platforms. The name "INI file" comes from the filename extension usually used, ".INI", that stands for "initialization". Sometimes, files using the INI file format will use a different extension, such as ".CFG", ".conf", or ".TXT".
Moar information is needed to tell you where the INI file is that you are looking for. Open an INI file in Notepad, but if you need to ask these questions then I wouldn't advise editing one.