Learn in the textbookAdvanced Threat Protection and Network Architecture / Communication Security
DefinitionA VPN builds a virtual private network that only subscribers or employees can use on top of a network shared by many users, so that it can be used much like a leased line.
ExplanationVPNs are used for remote work, where staff connect to the internal LAN from outside, and for linking distant offices. Two common forms are the Internet VPN (インターネットVPN), which runs over the internet, and the IP-VPN, which uses a closed network that a carrier provides only to its subscribers.
AnalogyIt is like digging a screened tunnel, open only to your own group, through a public road everyone travels. You share the same road, yet no one outside can see what goes on inside.
Memory hookVirtual Private Network: not a real dedicated line (virtual), yet usable as if it were your own (private). The name describes exactly what it is.