A Virtual Private Network, or VPN, is a network topology in which network traffic is routed to and from a remote endpoint in such a way that the endpoint can be reached from within a local network and its traffic is protected by encryption.
The primary use for a virtual private network is to safely enable users that are physically remote from an organizational network to participate in it as if they were a local node within the network, in a way that ensures that the network, the node, and the traffic passing between them all remain secure.
