A public subnet is a subnet that is configured to assign public IP addresses to instances
and which has a route to an Internet Gateway (which is created at the VPC level) configured
in the route table
NAT instances and NAT gateways are used by EC2 instances in private subnets (without public
IPs) to access the Internet
A VPN connection is used to establish a secure connection between the AWS cloud and an
on-premise data center or other cloud location. They are not used to access the Internet