NAT - Network Address Translation

Short for Network Address Translation, an Internet standard that enables a local-area network (LAN) to use one set of IP addressesfor internal traffic and a second set of addresses for external traffic. A NAT boxlocated where the LAN meets the Internet makes all necessary IP address translations.

NAT serves three main purposes:

Provides a type of firewallby hiding internal IP addresses

Enables a company to use more internal IP addresses. Since they're used internally only, there's no possibility of conflict with IP addresses used by other companies and organizations.

Allows a company to combine multiple ISDN connections into a single Internet connection.