hook_s adds all of the hooks from the Theme Hook Alliance into the starter theme _s, to make everyone happier.
By using hook_s as your starter theme, you allow plugin developers to use a set of standardized hooks that are in standard places in your theme.
Use hook_s, hack it apart, customize it, do what ever you want.
This theme, like WordPress and _s, is licensed under the GPL. Use it to make something cool, have fun, and share what you've learned with others.