<P> Network address translation (NAT) is a method of remapping one IP address space into another by modifying network address information in Internet Protocol (IP) datagram packet headers while they are in transit across a traffic routing device . The technique was originally used for ease of rerouting traffic in IP networks without readdressing every host . In more advanced NAT implementations featuring IP masquerading, it has become a popular and essential tool in conserving global address space allocations in face of IPv4 address exhaustion by sharing one Internet - routable IP address of a NAT gateway for an entire private network . </P> <P> IP masquerading is a technique that hides an entire IP address space, usually consisting of private IP addresses, behind a single IP address in another, usually public address space . The address that has to be hidden is changed into a single (public) IP address as "new" source address of the outgoing IP packet so it appears as originating not from the hidden host but from the routing device itself . Because of the popularity of this technique to conserve IPv4 address space, the term NAT has become virtually synonymous with IP masquerading . </P>

What is the meaning of nat in networking