Network adapter for Hyper-V

Can anyone help me to three different options to setup the network adapter ? From the article :

•External      : creates a connection from physical adapter and the virtual machine.
•Internal       : allows communications between virtualization servers and the virtual machine.
•Private : provides communication only among the virtual machines and allows the virtual machines to talk to each other only.

So, does it mean "External" means only the Hyper-V machine could communicate with the network card, but not the VM machine ? So, should I normally setup "Private" in order for Hyper-V server to comunicate with all these VM ? What is the actual use for these 3 settings ? Any examples to illustrate further ?

Thanks