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

The primary difference between a public and a private subnet in AWS is that a public subnet has direct internet access, while a private subnet does not. In a public subnet, resources such as EC2 instances can communicate with the internet directly through an Internet Gateway, which facilitates the routing of traffic to and from the internet.

This configuration allows instances in the public subnet to receive incoming traffic from the internet as well as send outbound requests. On the other hand, resources within a private subnet cannot directly access the internet. Instead, they rely on other means, such as NAT (Network Address Translation) gateways or instances, for outbound internet access, which helps to enhance security by keeping those resources hidden from direct internet exposure.

This distinction is critical in designing networking architectures in AWS, as it helps determine how resources can communicate both internally and externally. Understanding this difference is essential for implementing security measures and ensuring proper access controls in cloud environments.