In DAY 05 of my AWS series, I start from absolute basics—what an IP address actually is, why the internet is a “network of networks”, and why devices need unique addresses to communicate. I break down IPv4 vs IPv6 (why IPv4 is the older system and how address exhaustion pushed IPv6), and then I explain public vs private IPs in a way that directly connects to what you’ll see inside AWS. From there, I map these concepts to AWS: private IP on every instance, public IP when you want internet reachability, and Elastic IP when you need a static address that won’t change after restart. Then I move into the real AWS networking foundation: VPC (Virtual Private Cloud). I explain VPC like a secured commercial premise—boundaries, access, isolation—and why inside one AWS account you can create multiple VPCs that act like separate networks. After that, I cover the core building blocks you’ll hear all the time: subnets (public vs private), Internet Gateway vs NAT Gateway (and why private instances might still need outbound internet for updates/dependencies), and route tables (destination/target rules like 0.0.0.0/0). Finally, I begin the CIDR discussion by explaining IPv4 as 32 bits, and how network bits vs host bits work—so CIDR stops feeling confusing and starts feeling logical.