A Public IP prefix is a reserved range of static IP addresses that can be assigned to your subscription. You can use a prefix to simplify IP address management in Azure. Knowledge of the range ahead of time eliminates the need to change firewall rules as you assign IP addresses to new resources. This predictability significantly reduces management overhead when scaling in Azure. Public IP Prefix is available in all Azure public regions, Government cloud regions and China cloud regions.
For more information about Public IP prefixes in Azure and how to use them, see Public IP Prefix. If you're not familiar with public addresses, see Public IP addresses.