A subnet in AWS VPC (Virtual Private Cloud) is a range of IP addresses in your VPC that you can use to launch your resources, such as EC2 instances or RDS databases. A subnet is a subdivision of an IP network, which enables you to segment and isolate different parts of your network.
When you create a VPC, you can create one or more subnets within it. Each subnet must be associated with a specific availability zone within a region. Availability zones are physically separate locations within a region, each with its own power source, network, and connectivity to other availability zones.