Can someone explain how a skype phone works or internet phones similar?

What benefits do you get using a skype or internet phone. How does it work?
just wondering as im unsure.

skype vpn

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia��).