Azure Public IP

Public networks like the Internet communicate by using public IP addresses. Private networks like your Azure Virtual Network use private IP addresses, which aren't routable on public networks. To support a network that exists both in Azure and on-premises, you must configure IP addressing for both types of networks.

Public IP addresses enable Internet resources to communicate with Azure resources and enable Azure resources to communicate outbound with Internet and public-facing Azure services. A public IP address in Azure is dedicated to a specific resource, until it's unassigned by a network engineer. A resource without a public IP assigned can communicate outbound through network address translation services, where Azure dynamically assigns an available IP address that isn't dedicated to the resource.

Public Ip Addresses can be pulled from a Public IP Address Prefix, which is managed as its own resource.

Types

Azure Public IP addresses can be either static or dynamic IPv4 or Ipv6 Addresses.
Static Ip addresses keep the assigned number for as long as the resource exists, while dynamic addresses may change over the
lifespan of a resource. A common example on when a IP may change is when a Virtual Machine is power cycled.

SKUs

Azure Public IPs are available in 2 SKU's: Standard and Basic. General rule is that Standard is the standard, as most other services require standard.