The azurerm_subnet resource in Terraform is used to define and manage a subnet within an Azure Virtual Network (VNet). Subnets are logical subdivisions of a VNet, and they help you organize and segment your network resources. You can use the azurerm_subnet resource to create, update, or delete subnets as part of your infrastructure as code (IAC) deployment in Azure using Terraform.

Here’s an example of how to define an azurerm_subnet resource in a Terraform configuration:

In this example:

• azurerm_subnet is the resource type.
• "example" is the name given to this particular subnet resource, which you can use to reference it in other parts of your Terraform configuration.

The resource block specifies the following attributes:

• name: The name of the subnet.
• resource_group_name: The name of the Azure resource group where the subnet will be created. It is assumed that you’ve already defined an azurerm_resource_group resource elsewhere in your configuration.
• virtual_network_name: The name of the Azure Virtual Network where the subnet will be created. You should also have defined an azurerm_virtual_network resource earlier.
• address_prefixes: The IP address range (CIDR block) for the subnet. This determines the range of IP addresses that can be assigned to resources within the subnet.