How to do it...

1. Click on Subnets in VPC Dashboard. You can see that one default subnet is created in each AZ available in that region associated with the default VPC:

1. Click on Create Subnet link. Put the Name tag, select the VPC, CIDR range and Availability Zone. Click on Yes, Create:

1. A subnet is created with the Route Table and the Network ACL. We can select a subnet and, from the Subnet Actions menu, delete a subnet or modify other settings:

1. Click on the Route Table tab. You can see two entries, one for local VPC communication and the other for external communication through the Internet Gateway (starting with igw). The Internet Gateway enables resources hosted in AWS to communicate with the outside world. As the subnet is capable of communication with the external world through an Internet Gateway, it is a public subnet:

1. Click on Edit, so we can change the Route Table. If we associate a subnet with the Route Table that does not have an IGW attached to it, the subnet will act as a private subnet because the external world cannot connect through it. In the later section, we'll see how to create a route table.
2. You can delete a subnet by choosing the Delete option from the Subnet Actions menu.