It is a logically isolated section of the Google Cloud
We can choose a range of IPs using CIDR (Classless Inter-Domain Routing) Notation
In this network range we can launch Google Cloud Resources
Subnet is a logical partition of an IP network into multiple smaller network segments
This allows us to breakup your IP range of VPC into smaller networks
Public Subnet : IPs that can reach the internet
Private Subnet : IPs that cannot reach the internet