Answer Description
NAT (Network Address Translation) allows a router to translate IPs, both statically and dynamically. This allows an entire private network to share a single or group of public IP's to access the internet.
Wikipedia
Network address translation (NAT) is a method of mapping an IP address space into another by modifying network address information in the IP header of packets while they are in transit across a traffic routing device The technique was originally used to avoid the need to assign a new address to every host when a network was moved, or when the upstream Internet service provider was replaced, but could not route the networks address space It has become a popular and essential tool in conserving global address space in the face of IPv4 address exhaustion One Internet-routable IP address of a NAT gateway can be used for an entire private network
Network address translation - Wikipedia, the free encyclopedia