A network within a network for efficiently routing traffic. Defined by a range of consecutive IP addresses in a network, and can be used to limit access to other parts of the network.
Traffic moving within a defined subnet does not need to pass through a router, allowing data to transfer more quickly and reducing router bandwidth.
Subnet must have a CIDR block, and cannot overlap with existing subnet IP addresses.
Example
Subnet A: 10.0.0.0/26 (Would provide 10.0.0.0 - 10.0.0.63)
Subnet B: 10.0.0.64/26 (Would provide 10.0.0.64 - 10.0.0.127)
Public Subnets allow internet traffic routed through an internet gateway.
Private Subnets denies traffic routed from the internet, and requires a NAT devices to access the public internet.