“TOML” is a way of describing configuration. It is similar to and inspired by Microsoft’s “.ini” files. TOML can be easily translated into JSON objects which makes it a good choice for processing by programs. On the otherhand TOML can be easier for humans to type and read than JSON. It supports comments in the TOML files which can aid us humans when we need to review how we’ve setup things in the past.
See TOML language description at https://github.com/toml-lang/toml.