*`environment` :: This is the contains environment base logic and contains. At each step of the zsh loading process the `env_loader` function will load the corresponding file.
*`zlogin`/`zlogout`/`zprofile`/etc :: The default shell resource files. See [here](https://shreevatsa.wordpress.com/2008/03/30/zshbash-startup-files-loading-order-bashrc-zshrc-etc/) for more infomation on load order.