AWS NAT Gateway
AWS NAT Gateway, network address translation (NAT) gateway, is used to enable instances in a private subnet to connect to the internet or other AWS services, but prevent the internet from initiating a connection with those instances.
You are charged for creating and using a NAT gateway in your account. NAT gateway hourly usage and data processing rates apply. Amazon EC2 charges for data transfer also apply.
To create a NAT gateway, you must specify the public subnet in which the NAT gateway should reside. For more information about public and private subnets, see Subnet Routing. You must also specify an Elastic IP address to associate with the NAT gateway when you create it. The Elastic IP address cannot be changed once you associate it with the NAT Gateway. After you’ve created a NAT gateway, you must update the route table associated with one or more of your private subnets to point Internet-bound traffic to the NAT gateway. This enables instances in your private subnets to communicate with the internet.