amixer user space application

amixer user space application

I am going through amixer application, in this application there are two
open functons, snd_ctl_hw_open(&handle, NULL, card, 0) and
snd_ctl_open(&handle, card, 0)) , snd_ctl_hw_open(&handle, NULL, card, 0)
is interacting with the alsa kernel, but i am not getting what
snd_ctl_open(&handle, card, 0)) is exactly doing.