A ".cfg" file is a configuration file used by various software applications to store settings and preferences. These files are typically plain text, making them easy to read and edit with a simple text editor. They often contain key-value pairs that define how a program should behave or what options are available. Many video games, such as those developed by Valve or Electronic Arts, use ".cfg" files to allow players to customize their gaming experience. Additionally, software like Apache web server and Linux operating systems utilize these files to manage system configurations and user settings effectively.