A router is a networking device that forwards data packets between computer networks. Routers perform the “traffic directing” functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the Internet work until it reaches its destination node.
A virtual private network (VPN) extends a private network across a public network or Internet. It enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network. VPNs can provide functionality, security, and/or network management benefits to the user.
A firewall is a network security system that monitors and controls the incoming and outgoing network traffic based on predetermined security rules. A firewall typically establishes a barrier between a trusted, secure internal network and another outside network, such as the Internet, that is assumed not to be secure or trusted.