Config Folder

In your home directory, located /home/<username>, or simply ~, you will find a directory ~/.config. Directories prefixed with . are hidden by default so you will need to view it using ls -la (-a is the all flag).

In this directory lives all the configuration of installed applications. For example your neovim configuration will be in ~/.config/neovim.

If you are using a TWM, you usually put you configuration in here.

These are usually called dotfiles.