.conf / .cfg
Also known as: conf file, cfg file, config file, configuration file
A .conf or .cfg file is a plain-text configuration file holding the settings a program reads to control its behavior. There is no single standard — each app defines its own syntax — but most are human-readable key/value or sectioned text.
- Plain-text settings a program reads at startup
- No single standard — syntax varies per app
- Tiny, human-editable text files
What .conf and .cfg files do
These extensions mark a file as configuration: the options, paths, and parameters a program loads at startup. They are everywhere in servers and apps — web servers, system services, and games all read settings from .conf or .cfg files.
There is no one format behind the extension. One app’s .conf might look like INI-style sections, another like key/value lines, another like its own custom syntax. You read each app’s docs to know the rules.
Editing config files
Because they are plain text, you edit .conf and .cfg files in any text editor, and comment lines (often starting with #) explain the options. A typo can stop the program from starting, so back one up before editing.
Config files are tiny and never a storage concern. They are meant to be read and changed by people, not generated as bulk data.