Tunneling

The word tunneling (also spelled tunnelling) has more than one meaning.

• The literal meaning refers to the digging of tunnels.
• Tunneling can also refer to the exploration of utility tunnels by unauthorized people; see urban exploration.
• In physics, quantum tunneling involves the quantum-mechanical effect of transitioning through a classically-forbidden energy state.
• In computer networking, tunneling means the transmission of one data protocol encapsulated in another using a tunneling protocol. This technique often occurs in combination with encryption.
• Tunnelling appeared in the 1990s as a colloquial term for fraud committed by a company's own management or by major shareholders; see tunneling (fraud).