Router
A special-purpose computer (or software package) that handles the connection between 2 or more networks.
Routers spend all their time looking at the destination addresses of the packets passing through them and deciding which route to send them on.
Routers are similar to bridges, but provide additional functionality, such as the ability to filter messages and forward them to different places based on various criteria.
The Internet uses routers extensively to forward packets from one host to another.