network tunnel - Definition from the Hotspot Shield Glossary
A network tunnel is a path between two points on a network that is routed through other protocols or encapsulation processes using secure transmission. A tunnel is usually created between two private networks over a public network using encapsulation to ensure its security and integrity - The data packets will appear to belong to the public network, when in fact they contain the tunnel and private data.
The data in a tunnel is broken down into individual packets which are encrypted, and the packets are then encapsulated within the public network data and transmitted. Methods of tunneling include PPTP (Point to Point Tunneling Protocol) and L2TP (Layer Two Tunneling Protocol). A network tunnel is an extremely useful device for transmitting secure data in a large corporation.