What is the difference between a public and private subnet in a VPC?

The distinction between a public and private subnet in a VPC primarily revolves around internet accessibility.

A public subnet is characterized by having a route to an internet gateway, which allows resources within that subnet, such as EC2 instances, to communicate directly with the internet. This makes it ideal for resources that need to be accessible from outside the VPC, like web servers.

Conversely, a private subnet lacks a direct route to the internet. This means that any resources within a private subnet cannot be accessed directly from the internet. They may still reach the internet through a Network Address Translation (NAT) gateway or instance, but they do not have a public IP address.

This fundamental difference in connectivity to the internet is what defines the classification of subnets as public or private. Hence, stating that a private subnet has no route to the internet accurately captures this key characteristic.