NAT or "Network Address Translation"
If you have more than one computer in your home or small office, you'll need to use Network Address Translation, or NAT, to share a single Internet Address with them. NAT is both a blessing and a curse. It can form the basis for an effective hardware firewall, isolating your local computers from unsolicited and unwanted Internet traffic, but it complicates your ability to publish information or services. Learn exactly how it works with these movies: