A public IP address is a dynamic or static IP address that you can assign to virtual machines, load balancers, and virtual network gateways to communicate with the Internet. Your public IP addresses are associated with your Azure subscription, and can be moved freely between Azure resources. The address of dynamic public IP address may change when dissociated and moved between resources, or when the associated resource is shutdown or deleted. You can use a static public IP address to ensure that the assigned address remains the same, even if the associated resource is shutdown or deleted.
In the Classic deployment model, a public IP address was named an instance-level public IP (ILPIP) address when assigned to a virtual machine or role instance directly, and a virtual IP address (VIP) when assigned to a cloud service. Furthermore, a reserved IP address could be associated to the VIP of a cloud service to ensure that the assigned address remained the same even if its virtual machines or deployments were stopped. These concepts have now been unified in the Resource Manager deployment model with the public IP address resource.