A VPN involves the establishment of a virtual point-to-point connection using dedicated circuits or secure tunneling protocols over a shared or public network. VPNs authenticate remote users and assign them internal addresses (via NAT) so that they can be tracked. With site-to-site VPNs, all addresses are internally routed as one network.
VPNs that are used through a public network offer benefits similar to a wide area network (WAN).